The 2011 Illinois Marathon took place from Friday, April 29, 2011, to Saturday, April 30, 2011. New this year was the option of a 10k race in addition to the continuing full marathon, half marathon, marathon relay, 5k, and youth run. Additionally, the 5K was now held the Friday evening before the Saturday races. This enabled the additional I-Challenge component of the race, which is an optional "challenge" consisting of running both the Friday evening 5k and the full or half marathon on Saturday. Participants in the I-Challenge received an additional I-Challenge medal along with the medals for the two individual races.
