Whelan, 27, won three caps for Ireland last season, playing against Essex, South Africa and India. He took just the three wickets for his country, but his victims included Ravi Bopara, AB de Villiers, and most memorably, Sachin Tendulkar. Whelan was one of five reserves on stand-by for the World Cup, but wasn't required in the Caribbean.
"The main reason is commitment," he explained. "I have been involved with the Irish Squad for the best part of six years and I have always given 100% throughout. I no longer feel I can give that same commitment; therefore it would be unfair to the other Squad members, Trent and Phil to continue.
"I have thoroughly enjoyed all my cricketing experiences and I would like to take this opportunity to thank all those who helped me along the way, especially all the coaches that worked with me over the years and everyone at Railway Union. I wish Trent and the Irish lads the best of luck in the future."
Whelan has also confirmed that he won't be playing domestic cricket for Railway Union in the Leinster league this coming year, and that will be a major blow to them as they look to gain promotion back to Senior A following their relegation in 2007.
An Irish Cricket Union spokesman said, "We'd like to thank Roger for all his efforts over the past six years, and wish him all the best in the future."