The cycle of Eimeria acervulina was grown in primary culture of cells of three-week-old-chicken kidneys. EHT medium (Eagle, Hydrolysate of Lactalbumine, Bacto-Tryptose phosphate) allowed the development of this coccidium. 44 hours after infestation of the cells with sporozoites, the first schizonts appeared. The merozoites of first generation were released after 54 hours. They invaded the neighbouring cells and developed in them into schizonts of second generation mature after 68 hours. After 72 and 93 hours, a third and a fourth generation of schizonts were noticed. Merozoites IV create the Gamogony. To obtain the gamogony in vitro, we inoculated the cultures with merozoites IV recovered from axenic animals. The oocysts were released into the medium 45 hours after inoculation.