Twelve sets of five littermate barrows were utilized to determine the folic acid needs of a high lean genetic strain of pigs experiencing a low level of immune system activation. Pigs were penned individually and given ad libitum access to a corn, soybean meal, 27% milk product diet containing dietary concentrations of folic acid equivalent to 100, 200, 300, 400, and 500% of the current NRC (2) estimated requirement for 11 to 22 lb pigs. Pigs were started on test when the average litter weight reached 19 pounds and were taken off test as individual pigs reached a body weight of 51 pounds. Dietary folic acid concentration did not alter daily body weight gain, daily feed intake, feed:gain ratio, or rates of body protein and fat accretion. Based on these data, a dietary folic acid concentration of 0.14 mg per pound of feed is adequate to support optimal growth and body nutrient accretion in high lean growth pigs fed corn-soybean meal-milk product diets from 19 to 51 pounds.