Young-of-the-year hatchery reared rainbow trout, Salmo gairdneri, were used to estimate the rate of gastric evacuation of meals of oligochaetes and commercial pellets at water temperatures of 5, 10, 15, and 20 C. Different regression models produced different predictions for 25, 50, and 100% stomach emptying times for pellet meals consumed at 15 C. Greatest variation occurred when predicting time required for 100% stomach evacuation. Estimates ranged from 22 to 35 h for a substantial 13-h difference. Because the semilog model consistantly produced the highest F regression and the lowest F deviation it was selected as best for describing the data. Rate of gastric evacuation increased with increased temperature. Differences were greatest between 0 and 5 C and least between 15 and 20 C. An increase of 5 C at the low end of the temperature range produced a much greater absolute effect than at the high range. Depending on food type, it took 3 to 4 times as long to empty the stomach by 50% or 100% at 5 C as it did at 20 C. Time to empty the stomach increased from a minimum of 16.4 h at 20 C for both foods to 58.5 h and 72.4 h at 5 C for oligochaetes and pellets, respectively.