Five experiments were conducted to evaluate the effect of dietary supplemental folic acid(FA) in starting broiler chicks. In the first two experiments, basal diets based on corn and soybean meal contained 0.6 mg/kg FA but no supplemental methionine or choline. At 18 d of age, chicks showed curvilinear responses to folic acid supplementation with maximum growth and feed efficiencies at 1.45 mg/kg FA diet. The liver FA response was also curvilinear but reached a plateau at 1.70 mg/kg FA diet. The basal diet for 3 additional experiments contained soybean meal that had been washed with methanol to remove most of the choline. The diet contained only 0.6 mg /kg folic acid and 754 mg /kg choline. Chicks exhibited a larger growth response to folic acid at low choline levels as evidenced by a significant FA x choline interaction. FA supplementation increased but then decreased valgus leg deformity. Choline supplementation also decreased the incidences of valgus and varus leg deformities and decreased bone ash and increased the incidence of tibial dyschondroplasia. It is concluded that chicks fed diets based on practical ingredients require from 1.45 to 1.70 mg /kg FA diet and also 1.60 mg/kg FA when choline is offered near the NRC recommended level of 1,300 mg/kg.