Adult pocket gophers, fed diets of natural vegetation in the laboratory during summer and winter, remained in positive N balance in all feeding trials. Nitrogen budgets for free-ranging pocket gophers were calculated and revealed that total N influx exceeded 2400 mg N . kg-1 day-1 in summer and 2300 mg N . kg-1 day-1 in winter. Apparent N assimilation was 50 and 53% in summer and winter, respectively, and truly digestible N requirements were congruent to 680 mg N . kg-1 day-1. These budgets indicate that, in spite of seasonally-changing quality of available forage, pocket gophers remain in positive N balance, due largely to shifts in forage preference with season.