The objective of this study was to investigate the effect of acidified whole milk fed at 10 % of body weight on calf performance, and the incidence of scours, Twenty Holstein calves were assigned to one of two dietary treatments (whole milk or acidified whole milk), each consisting of 10 calves (5 male and 5 female), from d 5 to d 46 of age for a 42-d trial. Calves were fed either warm whole milk (35 to 37 degrees C) or acidified cold whole milk (acidified with formic acid to pH 4.8 and given at 10 to 20 degrees C) from nipple pails twice daily at 10 % of body weight. The amounts of milk given were adjusted weekly according to body weight, and the calves were gradually weaned, starting at d 40 of age. During the experiment, the calves were offered pelleted starter, alfalfa hay and water For ad libitum intake. All the calves were housed in individual pens. Body weight was recorded weekly. Fecal consistency scores were recorded daily on a scale of 1 to 4 (1=normal, 2=soft 3=runny and 4=watery). intakes of whole milk, starter, and total dry matter from milk and starter were similar between the treatments. Average daily body weight gains (d 5 to 46) for carves Fed whole milk, and acidified whole milk were also similar (427.44 and 459.95 gld, respectively). There was no significant difference in the efficiency of leed conversion between the treatments. Calves fed acidified whole milk exhibited lower fecal consistency scores than did calves led whole milk (2.04 vs, 2.33 during d 5 to 25 and 1.34 vs. 1.46 during d 26 to 46) even though the differences between treatments were not significant. The percentage of calf days with scours was significantly higher for calves fed whole milk than for those fed acidified whole milk for d 5 through 25 (34.28 vs. 18.57 %). In the same period, the percentage of calf days treated for scours was 8.57 % for calves fed whole milk while there was no incidence of scours requiring treatment in carves fed acidified whole milk. The cost of body weight gain was quite high for carves fed whole milk compared with those fed acidified whole milk, due mainly to the costs of veterinary treatment for scours ($ 3.76 vs. $ 2.68 / kg gain).