The study was carried out with the aim to determine the effects of different sowing dates on protein content, total sugar and dry matter rate of sweet corn in 2009 and 2010 under Isparta ecological conditions of Turkey. The research included five sowing dates 1 April, 15 April, 1 May, 15 May and 1 June. Different sowing dates had a significant effect on protein, total sugar and dry matter content of fresh sweet corns in both the years. Generally, the protein content (4.01 and 3.95%, respectively) and sugar amount (17.31 and 15.81 mg/100 g, respectively) of fresh sweet corn with optimal sowing date (1 May) were higher than those early and late sowing dates in 2009 and 2010. Dry matter ratio decreased when sowing for both the years delayed. The highest dry matter was obtained from April 1 sowing date (34.66 and 35.77%, respectively) in 2009 and 2010.