1. 1. Seasonal variation in total lipids was examined in several body components of the turtle Sternotherus odoratus. 2. 2. Carcass fat stores in both sexes were depleted during winter. Additionally, a decline in carcass lipids was associated with increases in gonadal mass. 3. 3. Concentrations of liver lipids were maximal during August and minimal during winter. 4. 4. Males showed little seasonal change in plasma lipid levels, whereas females had seasonal peaks temporally associated with ovarian development and carcass fat storage. 5. 5. Ovarian concentrations of lipids were minimal after nesting and increased during fall. 6. 6. Results suggest that S. odoratus uses stored fats both for reproduction and maintenance during winter. © 1982.