The effects of keeping farm mink in pairs or singly from weaning to pelting on haematological, clinical-chemical and stress physiological variables, on body and organ weight, and on fur properties were examined in 96 mink kits in order to assess the consequences on welfare and productivity. Mink kept in pairs had better pelt quality than mink kept singly. No significant difference was found in frequency of hair chewing between mink in pairs and single mink. Bite marks on the leatherside of the pelt occurred only in mink kept in pairs. No significant difference was found between the groups in body weight, and organ weight corrected for body weight. Based on the physiological variables applied, no differences in welfare were shown between mink in pairs and single mink. Sexual differences were found for the enzymes ASAT and ALAT, for number of leucocytes, and for adrenal glands relative to body weight.