Forty-four adult (;;'2.5 years) white-tailed deer (Odocoileus virginianus) does were separated into 9 groups. Each group was offered a paired combination diet of high, medium, or low protein; and high, medium, or low digestible energy (DE) for a 60-day period ending December 1983 (Study I). Forty-six adult does were maintained on a paired combination diet of high or low protein and high or low digestible energy for a 6-month period ending December 1984 (Study II). Thyroid gland activity data were collected only from deer in Study II. Thyroid activity based on cell height was greater at high than at low protein (P ≤ 0.05). Ovarian activity and thymus weight data were collected from deer in Studies I and II. Number of corpora lutea in Study I was greater at medium protein than at high or low protein and greater at high and medium energy than at low energy (P ≤ 0.05). Mean size of the 5 largest ovarian follicles in Study II was greater at high than at low protein (P ≤ 0.01). Cervical thymus weights in Study I were greater at high than at low energy (P < 0.05). No protein x energy interactions were observed for variables investigated in either study (P > 0.05).