Liver function was estimated quantitatively as the capacity of urea-N synthesis (CUNS), the galactose elimination capacity (GEC) and the antipyrine plasma clearance (APC) in rats following 24, 48, and 96 h of food deprivation. CUNS rose to a maximum following 24 h of starvation, then decreased to the control value at 48, 72, and 96 h (p = 0.02). GEC decreased following starvation, significant so at 48 h (p = 0.02). APC decreased at 48, and 72 h (p = 0.01), but rose to the control value at 96 h. It is concluded that a precise standardisation of starvation is important for interpretation of minor changes in CUNS, GEC, and APC.