Effects of dietary protein levels ranging from 35% to 15% of metabolizable energy (ME) and dietary fat levels ranging in a reciprocal fashion from 47% to 67% of ME, and a constant dietary carbohydrate level of 18% of ME were investigated in male mink kits in the growing‐furring period. Growth performance, mortality rate, hepatic fatty infiltration, weights of body and liver, relative weight of liver, haematocrit values, plasma activities of alanine‐aminotransferase (ALAT), aspartate‐aminotransferase (ASAT) and creatine‐kinase (CK), and plasma concentrations of chemical parameters were studied. A protein supply of 30% of ME supported normal growth performance and ensured a low mortality rate. Plasma ALAT and hepatic fatty infiltration increased with decreasing ME from protein. Alanine‐aminotransferase was found to be a useful tool in estimation of the incidence of hepatic fatty infiltration. The haematocrit values and the plasma values of total protein, urea, creatinine and bile acids were influenced by the dietary protein level.