A total of 2,439 potential Illinois waterfowl hunters returned questionnaires for the 2009-2010 Illinois Waterfowl Hunter Survey (53% response rate). Of the usable returns (2,398), 1,920 (80%) were from respondents who purchased an Illinois Migratory Waterfowl Stamp for the 2009-2010 seasons. These stamp purchasers included 1,616 (67%) individuals who hunted waterfowl in Illinois in 2009-2010.Based on waterfowl hunting licenses and stamps sold, we estimated 59,987 Illinois waterfowl hunters spent an estimated 1,222,980 days hunting during the 2009-2010 season, and harvested an estimated 613,335 waterfowl. There were an estimated 15,436 September Teal hunters; they spent an estimated 55,139 days hunting, and they harvested an estimated 19,222 Teal. During the regular duck season, 49,648 hunters spent 626,832 days hunting and harvested an estimated 228,211 Mallards, 41,549 Wood Ducks, and 129,795 other ducks, for a total of 399,555 ducks and 3,904 coots. During the regular goose season, an estimated 44,601 hunters spent 473,769 days hunting and harvested 142,836 Canada Geese and 17,382 other geese. The harvest of all geese during the regular goose season in 2009-2010 was estimated at 160,218 birds, compared to a total goose harvest of 160,762 in 2008-2009. Most duck hunters (22,264) were active in the Central Zone, spent 290,800 days hunting, and harvested 184,636 ducks. The North and South Zones accounted for 13,803 and 13,061 duck hunters and 67,500 and 143,459 ducks harvested, respectively. An estimated 0.64 ducks were harvested per hunter per day, and 8.05 ducks harvested per hunter during the entire 2009-2010 season. An estimated 15,102 hunters participated in the early September Canada goose season; 54% of September goose hunters were active in the Central Zone. The 2009-2010 harvest of Canada geese during the September season was estimated to be 16,212 birds. Most respondents reported identifying themselves as waterfowl hunters and considered waterfowl hunting one of their most important recreational activities. 3Most duck and goose hunters (81%) have participated in waterfowl hunting every year in the past five years. A majority of those hunters also served as waterfowl hunting mentors. Hunters’ preference for the week they would like to hunt in was variable, likely due to the high number of survey choices and variable hunting preferences for hunters within a zone. The most preferred dates for North Zone hunters were the first (13%) and second week (13%) of November and the third week (13%) of October. Among Central Zone hunters, the third (17%), fourth (14%), and second week (14%) of November represented the most desirable dates. South Zone hunters preferred the fourth week (15%) of November, the second week of December (14%), and the third week of November (11%). A plurality of North and Central Zone duck hunters (36%, and 42%, respectively) preferred the average opening date of duck season near October 25, and the closing date near December 23, 2010. A plurality of South Zone duck hunters preferred the average opening date near November 30, and closing date near January 28. South Zone hunters exhibited no clear preference as to whether they want opening day to fall on Thanksgiving Day or the day after. Most duck hunters in all zones (North, Central, and South) would support a split duck season; however, in the Central Zone there was no difference (42% vs. 41%). Duck hunters in the North and Central Zones prefer the season dates for the split season to fall between October 19-27 and November 9-December 29. In the South Zone, the majority of duck hunters prefer the split duck season to start between November 13-18 and December 3-January 25.