The 2011 Rijeka Open (also known as the 2011 Rijeka Open powered by INA for sponsorship purposes) was a professional tennis tournament played on clay courts. It was the fifth edition of the tournament which was part of the 2011 ATP Challenger Tour. It took place in Rijeka, Croatia between 30 May and 5 June 2011.
The following players received wildcards into the singles main draw:
The following players received entry as an alternate into the singles main draw:
The following players received entry from the qualifying draw:
Rui Machado def. 
Grega Žemlja, 6–3, 6–0[1]
Paolo Lorenzi / 
Júlio Silva def. 
Lovro Zovko / Dino Marcan, 6–3, 6–2
