Seasonal changes in blood glucose content, liver glycogen content, and fat body weight have been studied in Rana pipiens. Over a 12-month period frogs were maintained at room temperature in tap water for a minimum of 14 days before observations were made. The frogs were not fed while in the laboratory. Blood glucose content was high in the summer (June through August) and fall (September through November) and low in the winter (December through February) and spring (March through May). The value for summer (60 mgm per 100 cm3 blood) was not significantly different from the blood glucose level in the fall (60 mgm % ). However, the blood glucose content in the winter (52 mgm % ) and the spring (49 mgm % ) were significantly different from each other and from the summer and fall. Liver glycogen content was high in the fall (1.16 gm/100 gm body weight). This decreased through the winter (0.85 gm/100 gm body weight) and spring (0.50 gm/100gm body weight) until the annual low was reached in the summer (0.27 gm/100 gm body weight). All seasons were significantly different from each other when tested statistically. Fat body weights also exhibited a seasonal variation. All seasons were significantly different from each other. The high was in the summer (203.3 mgm/100 gm body weight). Fat body weights then decreased to 87.1 mgm/100 gm body weight in the fall, 32.7 mgm/100 gm body weight in the winter, and 25.1 mgm/100 gm body weight in the spring. These data are important when studying metabolic changes in this common laboratory animal.