Beef top round roasts weighing approximately 2.3 lb. each were cooked from the thawed and frozen states in a countertop microwave oven (115v; 2,450 mHz) at the cooking power levels of "high" (553 watts) and "simmer" (237 watts) and also in a conventional oven at 163 degrees C (325 degrees F). Cooking times, energy consumption, cooking losses, and palatability of cooked products were compared. In general, no notable advantages were found in cooking at microwave "simmer" vs. "high".