**Exhibit 8.1**

**SUBSIDIARIES OF ARCADIS N.V.**

**CONSOLIDATED COMPANIES (as of December 31,2005)**

 
| Entity                                                     | ** ** | **Jurisdiction** |
|------------------------------------------------------------|------------|------------------|
| ARCADIS G &  M, Inc.                         |       | Delaware         |
| ARCADIS Nederland B.V.                                     |       | The Netherlands  |
| ARCADIS Europe B.V.                                        |       | The Netherlands  |
| ARCADIS USA B.V.                                           |       | The Netherlands  |
| ARCADIS Latin America  B.V.                                |       | The Netherlands  |
| ARCADIS International  B.V.                                |       | The Netherlands  |
| PRC B.V.                                                   |       | The Netherlands  |
| ARCADIS Asia B.V.                                          |       | The Netherlands  |
| AYH plc Holding                                            |       | United Kingdom   |
| ARCADIS North America                                      |       | Colorado         |
| ARCADIS Construction  Services LLC                         |       | Colorado         |
| ARCADIS Corporate  Services, Inc.                     |       | Colorado         |
| ARCADIS G&M of  Michigan, LLC                          |       | Michigan         |
| Reese, Macon and  Associates, Inc.                    |       | Florida          |
| ARCADIS G&M of  Ohio, Inc.                        |       | Ohio             |
| Lawson,  Noble & Webb, Inc.                  |       | Florida          |
| ARCADIS US  Holdings, Inc.                            |       | Colorado         |
| Bessent,  Hammink & Ruckman, Inc.            |       | Florida          |
| Diversity  Partners, Inc.                             |       | Maryland         |
| ARCADIS Peru Holdings,  LLC                                |       | Colorado         |
| ARCADIS Devolpment, LLC                                    |       | Colorado         |
| ARCADIS  Greystone, Inc.                              |       | Colorado         |
| Blasland,  Bouck & Lee, Inc.                 |       | NY               |
| ARCADIS  Capital, Inc.                                |       | Colorado         |
| Giffels Associates                                         |       | Mexico           |
| ARCADIS G&M of Ohio  A&E, LLC                      |       | Ohio             |
| Construction Dynamics  Group, Inc.                    |       | Maryland         |
| Lewis and Zimmerman  Associates, Inc.                 |       | Maryland         |
| ARCADIS G&M of  Michigan, LLC                          |       | Michigan         |
| CDG International, Ltd                                     |       | United Kingdom   |
| ARCADIS G&M del  Peru, SAC                             |       | Peru             |
| Clear Creek Station,  LLC                                  |       | Colorado         |
| Rivertown Development  LLC                                 |       | CA               |
| Greystone Environmental  Consultants, Inc. Arizona    |       | Colorado         |
| Greystone Environmental  Consultants, Inc. California |       | Colorado         |
| Greystone Environmental  Consultants, Inc. Colorado   |       | Colorado         |
| Greystone Environmental  Consultants, Inc. Wyoming    |       | Colorado         |
| Greystone  Canada, Inc.                               |       | Canada           |
| BBL Envrionmental  Services, Inc.                     |       | Florida          |
| Triangle Economic  Research, LLC                           |       | NC               |
| Glacier Creek Properties  Companies                        |       | NY               |
| Cranbury Properties  Company                               |       | NY               |
| ARCADIS Regio B.V.                                         |       | The Netherlands  |
| ARCADIS PlanRealisatie  B.V.                               |       | The Netherlands  |
| ARCADIS Geo- en  Vastgoedinformatie B.V.                   |       | The Netherlands  |
| B.V. Boreon                                                |       | The Netherlands  |
| Onroerend Goed  Balkenweg B.V.                             |       | The Netherlands  |
| ARCADIS Infra B.V.                                         |       | The Netherlands  |
| ARCADIS Support B.V.                                       |       | The Netherlands  |

 

----

 
| ARCADIS Euroconsult B.V.                                        |   | The Netherlands |
|-----------------------------------------------------------------|--------|-----------------|
| ARCADIS Bouw en  Vastgoed B.V.                                  |   | The Netherlands |
| ARCADIS FM Beheer B.V.                                          |   | The Netherlands |
| ARCADIS Enterprises  B.V.                                       |   | The Netherlands |
| ARCADIS Ruimte en  Milieu B.V.                                  |   | The Netherlands |
| LB&P Ecologisch  Advies B.V.                                |   | The Netherlands |
| ARCADIS Projecten B.V.                                          |   | The Netherlands |
| Stedebouwkundig  Adviesbureau Witpaard-Partners B.V.            |   | The Netherlands |
| Micon Bedrijfsadviseurs  Milieu B.V.                            |   | The Netherlands |
| Serasea B.V.                                                    |   | The Netherlands |
| Heidemij Realisatie 3  B.V.                                     |   | The Netherlands |
| Copijn Utrecht Holding  B.V.                                    |   | The Netherlands |
| Heidemij Realisatie  Deutschland GmbH                           |   | Germany         |
| Glastuinverplaatsing Leidsche  Rijn B.V.                        |   | The Netherlands |
| Ontwikkelings  Maatschappij Floris V CV                         |   | The Netherlands |
| Bio Science Park I B.V.                                         |   | The Netherlands |
|  B.V. Venlo TPN                                            |   | The Netherlands |
| ROW de Ruiter B.V.                                              |   | The Netherlands |
| Stationswijk B.V.                                               |   | The Netherlands |
| Heidemij Realisatie II  B.V.                                    |   | The Netherlands |
| Heidemij Realisatie I  B.V.                                     |   | The Netherlands |
| Konijn Hoorn  Machinebouw B.V.                                  |   | The Netherlands |
| Copijn Utrecht B.V.                                             |   | The Netherlands |
| Copijn Utrecht  International Tree Services B.V.                |   | The Netherlands |
| Copijn Utrecht Tuin en  Landschapsarchitecten B.V.              |   | The Netherlands |
| Copijn Utrecht  Eurobomen B.V.                                  |   | The Netherlands |
| Copijn Utrecht  Boomchirurgen B.V.BA                            |   | Belgium         |
| Copijn Luxemburg SA                                             |   | Luxembourg      |
| Atlantis GmbH                                                   |   | Germany         |
| Vastgoed Data B.V.                                              |   | The Netherlands |
| KLM Aerocarto B.V.                                              |   | The Netherlands |
| Ilis B.V.                                                       |   | The Netherlands |
| KLM Aerocarto NV                                                |   | Suriname        |
| Transcad Ltd                                                    |   | Egypt           |
| KLM Aerocarto Belgium  B.V.BA                                   |   | Belgium         |
| Autarcis B.V.                                                   |   | The Netherlands |
| ARCADIS BMB Management  Consultants B.V.                        |   | The Netherlands |
| Ilis/GMI B.V.                                                   |   | The Netherlands |
| Ilis/Ilaco B.V.                                                 |   | The Netherlands |
| Environmental Forestry  Development                             |   | The Netherlands |
| GP Kenia B.V.                                                   |   | The Netherlands |
| Ingenieursbureau  Grabowsky & Poort International B.V. |   | The Netherlands |
| ARCADIS Caribbean N.V.                                          |   | Curacao         |
| ARCADIS St. Maarten  N.V.                                       |   | St. Marteen     |
| ARCADIS Curaçao N.V.                                       |   | Curaçao    |
| ARCADIS Bonaire N.V.                                            |   | Bonaire         |
| Grabowsky&Poort  Puerto Rico Inc.                           |   | Puerto Rico     |
| ARCADIS AQUMEN Facility  Management B.V.                        |   | The Netherlands |
| ARCADIS Deutschland  GmbH                                       |   | Germany         |
| ARCADIS Ekokonrem Sp.z.o.o.                                     |   | Poland          |
| ARCADIS Belgium N.V.                                            |   | Belgium         |
| ARCADIS Holding France  S.A.                                    |   | France          |
| ARCADIS  Geraghty & Miller International Limited       |   | United Kingdom  |
| Profil Sp. Z o.o.                                               |   | Poland          |
| ARCADIS Polska Sp. z o  o.                                      |   | Poland          |
| ARCADIS Grabowski  Grabowska                                    |   | Poland          |

 

----

 
| ARCADIS UK Limited                                   |   | United Kingdom  |
|------------------------------------------------------|--------|-----------------|
| ARCADIS Consult GmbH                                 |   | Germany         |
| ACD Vermessung GmbH                                  |   | Germany         |
| ARCADIS Cert GmbH                                    |   | Germany         |
| ARCADIS Bauconsult GmbH                              |   | Germany         |
| ARCADIS Ingenieure  Halle GmbH                       |   | Germany         |
| ARCADIS Liegenschaftsentwicklung  GmbH               |   | Germany         |
| ARCADIS HOMOLA AG                                    |   | Germany         |
| LGU Labor fur  Geotechnik und Umwelt GmbH            |   | Germany         |
| ARCADIS  Projektmanagement s.r.o.                    |   | Czech Republic  |
| AYH Homola Projects  GmbH                            |   | Germany         |
| ECO2 Sp. z o o.                                      |   | Poland          |
| Starke Diekstra N.V.                                 |   | Belgium         |
| ARCADIS Gedas N.V.                                   |   | Belgium         |
| ARCADIS Lapere N.V.                                  |   | Belgium         |
| ARCADIS Fally N.V.                                   |   | Belgium         |
| ARCADIS Domus FM                                     |   | Belgium         |
| S.W.K. N.V.                                          |   | Belgium         |
| Constructor N.V.                                     |   | Belgium         |
| CW N.V.                                              |   | Belgium         |
| ARCADIS FCI S.A.S.                                   |   | France          |
| Europe Etudes Gecti  (EEG)                           |   | France          |
| ARCADIS ESG                                          |   | France          |
| Sobesol                                              |   | France          |
| Geotechnika                                          |   | Czech Republic  |
| Mecasol                                              |   | France          |
| Eurometudes                                          |   | Rumania         |
| GOEFOS                                               |   | Slovakia        |
| Terence E  Dudley & Associates              |   | United Kingdom  |
| ARCADIS Chile S.A.                                   |   | Chile           |
| ARCADIS Brasil Ltda                                  |   | Brazil          |
| ARCADIS US  Holding, Inc.                       |   | Delaware        |
| ARCADIS Geotecnica S.A.                              |   | Chile           |
| GC Consultores  Geotecnicos                          |   | Peru            |
| Geotecnica Consultores  Ltd                          |   | Argentina       |
| Arcadis Geotécnica Bouw  Infra Ltda.            |   | Chile           |
| Consorcio Arcadis  Geotecnica Mimetal Ltda.          |   | Chile           |
| Inversiones de  Infraestructura Cabo de Hornos Ltda. |   | Chile           |
| ARCADIS Logos  Engenharia S.A.                       |   | Brazil          |
| ARCADIS Logos Energia  S.A.                          |   | Brazil          |
| Enerconsult S.A.                                     |   | Brazil          |
| ARCADIS Hidro-Ambiente  S.A.                         |   | Brazil          |
| ARCADIS Tetraplan S.A.                               |   | Brazil          |
| PRC Training B.V.                                    |   | The Netherlands |
| ARCADIS Construction Consulting  co, ltd             |   | Shanghai        |
| AYH ESOP Ltd                                         |   | United Kingdom  |
| AYH Sarl                                             |   | France          |
| AYH Homola Polska Sp  zoo                            |   | Poland          |
| AYH Brown Ltd                                        |   | Scotland        |
| Summerfield Robb Clark  Ltd                          |   | Scotland        |
| Robert Shanks Projects  Ltd                          |   | United Kingdom  |
| Noble Projects  Management Ltd                       |   | United Kingdom  |
| PMGlobal UK Ltd                                      |   | United Kingdom  |
| Homola AYH Ltd                                       |   | United Kingdom  |
| SMP / AYH Ltd                                        |   | Ireland         |
| AYH Mace Ltd                                         |   | United Kingdom  |

 

----

 

**NON-CONSOLIDATED COMPANIES**

 
| Entity                                                          | ** ** | **Jurisdiction** |
|-----------------------------------------------------------------|------------|------------------|
| Stichting Fagoed                                                |       | The Netherlands  |
| Dynamicon B.V.                                                  |       | The Netherlands  |
| EMDEME SA                                                       |       | Portugal         |
| Ecosystems B.V.                                                 |       | The Netherlands  |
| Combinatie  Oost-Achterhoek B.V.                                |       | The Netherlands  |
| Urbanet B.V.                                                    |       | The Netherlands  |
| Brainliner B.V.                                                 |       | The Netherlands  |
| Vermeer-Heidemij v.o.f.                                         |       | The Netherlands  |
| Waterwolf  Dienstverlening Buitenruimte B.V.                    |       | The Netherlands  |
| Siberië CV                                                 |       | The Netherlands  |
| Bio Science Park CV                                             |       | The Netherlands  |
| Grubbenvorst v.o.f.                                             |       | The Netherlands  |
| VOF Meinga                                                      |       | The Netherlands  |
| Eurotree GmbH                                                   |       | Germany          |
| Guard B.V. i.o.                                                 |       | The Netherlands  |
| Adviseurs Bouwplan  Ontwikkeling BGN Partners B.V.              |       | The Netherlands  |
| Aronsohn ARCADIS  Oosterdokseiland VOF                          |       | The Netherlands  |
| Somerset                                                        |       | Maryland         |
| Sahelconsult Sarl,  Ouagadougou                                 |       | Burkina Faso     |
| Afid Consultants Sarl                                           |       | Senegal          |
| Euroconsult para  Latinoamerica y el Caribe SA.                 |       | El Salvador      |
| Darwish Consulting  Engineers                                   |       | Egypt            |
| Euroconsult Pakistan  Ltd.                                      |       | Pakistan         |
| Brazilian Venture  Consultants Ltda.                            |       | Brazil           |
| Ilaco do Brazil Ltda.                                           |       | Brazil           |
| Ilaco Suriname N.V.                                             |       | Suriname         |
| Eurasia Consult Ltd                                             |       | Kazachstan       |
| ARCADIS Konsult JSC                                             |       | Russia           |
| Surgroma N.V.                                                   |       | Suriname         |
| CV Oude Grachtpad                                               |       | The Netherlands  |
| Umweltlabor Westpfalz  GmbH                                     |       | Germany          |
| Interplan Environmental  Systems GmbH                           |       | Germany          |
| Eurolabors AG                                                   |       | Germany          |
| Braun &  Schlokermann-ARCADIS Planungsgesellschaft mbH |       | Germany          |
| EuroPartners Consult  Ltd.                                      |       | Kazachstan       |
| Jaakko Poyry Geotecnica  Ltd                                    |       | Chile            |
| Proyectos  Aeroportuarios Ltd                                   |       | Chile            |
| ORSA                                                            |       | Chile            |
| Consorcio Reg. GC JRI  Ing. Ltda                                |       | Chile            |
| Consorcio  Scetaroute-Grimaux, Varde, Geotécnica Ltda.     |       | Chile            |
| Consorcio Geotécnica  JRI S.A.                             |       | Chile            |
| Biogás Energia  Ambiental S.A.                             |       | Brazil           |
| PIE-RP Termelétrica  S.A.                                  |       | Brazil           |
| Cocal Termelétrica S.A.                                    |       | Brazil           |
| Cocal Termelétrica S.A.                                    |       | Brazil           |
| Breitener Energética  S.A.                                 |       | Brazil           |
| Hidropower Energia S.A.                                         |       | Brazil           |
| Tupan Energia Eletrica  S.A.                                    |       | Brazil           |
| V.O.F. Stationseiland                                           |       | The Netherlands  |
| V.O.F. De Ruijterkade                                           |       | The Netherlands  |
| V.O.F. X-Pact                                                   |       | The Netherlands  |
| V.O.F. Modieslab                                                |       | The Netherlands  |

 

----

 
| V.O.F. EMC STARC                                                                     |   | The Netherlands |
|--------------------------------------------------------------------------------------|--------|-----------------|
| Geodynamique et Structure                                                            |   | France          |
| Getu                                                                                 |   | Tunisia         |
| SEM Savoie Labo                                                                      |   | France          |
| Geomechanika, s.r.o.                                                                 |   | Czech Republic  |
| Solidex, a.s.                                                                        |   | Czech Republic  |
| Kamex, s.r.o.                                                                        |   | Czech Republic  |
| Geoprojekt, s.r.o.                                                                   |   | Czech Republic  |
| Terratech, spol. S.r.o.                                                              |   | Czech Republic  |
| Terratec, spol. S.r.o.                                                               |   | Czech Republic  |
| Geoinzenyring, s.r.o.                                                                |   | Czech Republic  |
| ZPD d.d.                                                                             |   | Croatia         |
| Innovated Tree Services  LLC                                                         |   | Delaware        |
| The GIS Foundation  Partnership (Joint Venture)                                      |   | North Carolina  |
| ARCADIS/BPA- Joint  Venture                                                          |   | Georgia         |
| Global Rail Consortium  LLC                                                          |   | Florida         |
| ARCADIS — ENERGY Y  Associados, SA (Consortium)                                 |   | Peru            |
| Encore Environmental  Consortium, LLC                                                |   | MI              |
| Environmental  Engineering Associates, LLP                                           |   | NY              |
| Blasland, Bouck & Lee/TAMS  Consultants, Inc. (New York Joint Venture) |   | NY              |

 

----