We determined maintenance nitrogen requirements of the adult prairie vole (Microtus ochrogaster) using a nitrogen balance trial approach. Prairie voles required 401 mg kg^−0.75 day⁻¹ of nitrogen to meet maintenance requirements and met requirements on diets containing approximately 4.4% crude protein. Dry matter intake did not vary with percentage of nitrogen in the diet, suggesting that animals on nitrogen-insufficient diets do not display appreciable compensatory intake. Body mass change was only moderately associated with nitrogen balance, indicating that fluctuations in body mass during the trial were likely associated with factors other than nitrogen intake.