Abstract: In the present study, seasonal variation of vitamin and sterol content of Chironomidae larvae were determined by using HPLC. As the result of vitamin analysis, we found α-tocopherol, retinol, K1, K2, D2 and D3. When the seasonal variation of vitamin groups were compared, a significant increase was observed in vitamin K1, K2, D2 and α-tocopherol in all seasons. A significant increase was observed in vitamin D3 in spring. And also vitamin A level high in autumn and winter. α-tocopherol level was significantly high among vitamins. When vitamin groups were compared statistically, differences were detected between seasons (p<0.001). Analyzing the content of sterol, we found ergosterol, cholesterol, stigmasterol and β-sitosterol in all seasons. Cholesterol level was found to be significantly high in sterols. When sterol contents were compared statistically, differences were detected between seasons (p<0.001). In conclusion, the reasons for these differences are larval development feature and the variety of food in different seasons.