This study was conducted to determine optimum sowing dates for sweet corn in the Southeastern Anatolia region. The research was carried out at the Agricultural Research Station of Harran University in Şanhurfa during 2000 and 2001. Sowing dates were April 25, May 10, May 25, June 10, June 25, July 10, July 25 and August 10. Based on the sowing dates, fresh ear yield, duration of tasseling, ear diameter, kernel numbers per ear, single fresh ear weight and husk ratio parameters were statistically significant (**P < 0.01) in both years. The highest fresh ear yields were 177.51 and 172.30 kg ha-1 for the 25 July sowing date in 2000 and 2001, respectively. The lowest fresh ear yields were 18.24 and 15.53 kg ha-1 for the April 25 sowing date in 2000 and 2001, respectively. Fresh ear yield decreased with early sowing dates (from April 25 to June 25) in both years. The results indicate that optimal sowing dates for sweet corn could be from June 25 to July 25 in Şanhurfa and similar Southeastern Anatolia regions. © TÜBITAK.