Between 1978 and 1997 the food consumption and growth of five Pacific Walrus Odobenus rosaries div-ergens pups were studied at Harderwijk Marine Mammal Park. Four wild-born pups were hand-reared on formula and one other pup, born at the Park in June 1995, was suckled by its mother. The two formulas used in this study are described, and the chemical composition and calorific content of one formula and of a sample of Walrus milk are provided. The four hand-reared pups (and all the hand-reared Walrus pups reported in the literature) had a lower mass than the suckled pup at similar ages. The suckled pup grew, on average, 18 kg/month during the first 6 months after birth. At the age of 13 months, when two pups were being weaned from formula to a fish diet, the mystacial vibrissae went through a growth spurt. Food passage times were measured by adding carmine red dye to the formula and the median initial passage time was 12 hours in one pup and 17 hours in the other.