Sulfaquinoxaline (SQ) was fed at the rate of 0.05% to chickens severely exposed to Coccidia. The drug was given 2 days out of 5, 1 day out of 4, 1 day out of 5,2 days out of 6,4 days out of 8, and at the rate of 0.0125% fed continuously. Results are given for 43,309 treated birds and 3,085 untreated controls. The deaths among the treated birds were 1.75, 2.17, 1.8, 0.86, 1.13, and 1.2% as compared to 17.43% in the controls. The birds which died showing E. necatrix were 0.63, 0.26, 0.28, 0, 0.13 and 0.12%, respectively, as compared to 7.45% in the controls. Thus, SQ used at the rate of 0.05% intermittently and 0.0125% continuously in the feed is effective in the control of E. tenella and E. necatrix infection in chickens. Toxicity was not observed.