US ONCOLOGY HOLDINGS, INC. AND US ONCOLOGY, INC.

Exhibit 21

Subsidiaries of the Registrant

(All are Delaware entities unless otherwise indicated)



|                                                           
|-----------------------------------------------------------
|US Oncology, Inc.                                          
|AccessMed Holdings, LLC                                    
|AccessMed, LLC (3)                                         
|US Oncology Corporate, Inc.                                
|AOR Real Estate, LLC                                       
|RMCC Cancer Center, LLC                                    
|AOR Management Company of Indiana, LLC                     
|AOR Holding Company of Indiana, LLC                        
|AOR of Indiana Management Partnership (2)                  
|AOR Management Company of Missouri, LLC                    
|AOR Management Company of Arizona, LLC                     
|AOR Management Company of Oklahoma, LLC                    
|AOR Management Company of Pennsylvania, LLC                
|AOR Management Company of Virginia, LLC                    
|AOR of Texas Management, LLC                               
|AORT Holding Company, Inc.                                 
|AOR Synthetic Real Estate, LLC                             
|Physician Reliance Network, LLC                            
|US Oncology Research, LLC (1)                              
|Physician Reliance, LLC                                    
|Iowa Pharmaceutical Services, LLC                          
|New Mexico Pharmaceutical Services, LLC                    
|North Carolina Pharmaceutical Services, LLC                
|SelectPlus Oncology, LLC                                   
|Nebraska Pharmaceutical Services, LLC                      
|US Oncology Pharmaceutical Services, LLC                   
|East Indy CC, LLC (2)                                      
|Greenville Radiation Care, Inc.                            
|St. Louis Pharmaceutical Services, LLC                     
|Texas Pharmaceutical Services, LLC                         
|TOPS Pharmacy Services, Inc. (1)                           
|Cancer Treatment Associates of Northeast Missouri, Ltd. (1)
|Southeast Texas Cancer Centers, LP (1)                     
|AOR Real Estate of Greenville, LP                          
|KCCC JV, LLC                                               
|Oregon Cancer Center, Ltd. (1)                             
|Colorado Cancer Centers, L.L.C. (4)                        
|The Carroll County Cancer Center, LP (1)                   
|US Oncology Specialty, LP                                  
|Oncology Rx Care Advantage, LP                             
|US Oncology Integrated Solutions, LP                       
|Oncology Today, LP                                         
|US Oncology Reimbursement Solutions, LLC                   
|The Oncology Portal, LLC                                   
|Unity Oncology, LLC                                        
|CCCN NW Building JV, LLC                                   
|Innovent Oncology, LLC                                     
|NexCura, LLC                                               
|US Oncology Clinical Development, LLC                      
|US Oncology Lab Services, LLC                              
|WFCC Radiation Management Company, LLC (1)                 



|(1) | Organized in the State of Texas
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|(2) | Organized in the State of Indiana
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|(3) | Organized in the State of Kansas
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|(4) | Organized in the State of Colorado
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