The effect of three coccidiostatic drugs including two sulpha (Esb3 and Noxal) and one non sulpha (Amprolsol) was observed in broiler chicks experimentally infected with coccidialoocysts. The birds treated with sulpha drugs developed hemorrhagic syndrome. The most characteristic findings were haemorrhages in the liver, spleen, kidneys, heart, proventriculus, gizzard and muscles of breast and thighs, but the disease was not observed in birds which were treated with non-sulpha drug. The hemorrhagic lesions in the infected-untreated birds were confined to the intensities and were absent in uninfected-treated birds.