----

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|                 |   |                                                                                                                                                                             |
|----------------------|--------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Exhibit Number  |   | Title                                                                                                                                                                       |
| 3.1                  |   | Description of the Memorandum and Articles of Association of the Company (incorporated by reference to exhibit 3.1 to the Form 20F (File No. 333-08704) filed on March 6, 2013). |
|                 |   |                                                                                                                                                                             |
| 12.1*                |   | Section 302 certifications.                                                                                                                                                      |
|                 |   |                                                                                                                                                                             |
| 12.2**               |   | Section 906 certifications.                                                                                                                                                      |
|                 |   |                                                                                                                                                                             |
| 21.1                 |   | List of Subsidiaries (incorporated by reference to Item 4 of Form 20-F) (File No. 333-08704) filed on March 23, 2016).                                                           |
|                 |   |                                                                                                                                                                             |
| 23.1*                |   | Consent of KPMG, Independent Registered Public Accounting Firm                                                                                                                   |
|  101.1**        |   |  Interactive Data Files (XBRL – Related Documents)                                                                                                                    |

| * | Filed herewith |
|---|----------------|

| ** | Previously filed with the Company’s Annual Report on Form 20-F, filed with the Securities and Exchange Commission on March 23, 2016. |
|----|--------------------------------------------------------------------------------------------------------------------------------------------|

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|                 |   | ICON plc                |
|----------------------|--------|-------------------------|
|                 |   |                    |
|                 |   |                    |
|                 |   |                    |
|                 |   | /s/ Brendan Brennan     |
| Dated: June 16, 2016 |   |                    |
|                 |   | Brendan Brennan         |
|                 |   | Chief Financial Officer |