The 2011 San Marino CEPU Open was a professional tennis tournament played on clay courts. It was the 24th edition of the tournament which was part of the Tretorn SERIE+ of the 2011 ATP Challenger Tour. It took place in City of San Marino, San Marino between 8 and 14 August 2011.
| Country | Player | Rank1 | Seed | |
|---|---|---|---|---|
 Italy | Potito Starace | 63 | 1 | |
 Czech Republic | Lukáš Rosol | 69 | 2 | |
| Italy | Filippo Volandri | 73 | 3 | |
 Spain | Pere Riba | 77 | 4 | |
| Rui Machado | 84 | 5 | ||
 France | Marc Gicquel | 101 | 6 | |
| Mischa Zverev | 115 | 7 | ||
| France | Benoît Paire | 117 | 8 |
The following players received wildcards into the singles main draw:
The following players received entry as a special exempt into the singles main draw:
The following players received entry from the qualifying draw:
See main article: 2011 San Marino CEPU Open – Singles. Potito Starace def. 
Martin Kližan, 6–1, 3–0, retired
See main article: 2011 San Marino CEPU Open – Doubles. 
James Cerretani / Philipp Marx def. Daniele Bracciali / 
Julian Knowle, 6–3, 6–4
