In order to understand the endogenous development of Eimeria flavescens,20 coccidia-free rabbits (Oryctolagus curiculus)were orally inoculated with E. flavescens sporulated oocysts and killed under anesthesia at intervals for collecting intestinal tissue samples. The samples were used for conventional paraffin section and H. E staining. Four asexual generations and one sexual generation. Two types of meronts and merozoites were found in each asexual generation:type A meronts gave rise to a smaller number of thick and short merozoites, while the type B meronts produced lots of thin and long merozoites. The first generation meronts were found in the crypts of the jejunum 60 - 72 h after inoculation (a. i. ). The second generation meronts were found in the crypts of the large intestine 84 h after inoculation. The third generation meronts developed in the villi of the large intestine 96 - 120 h after inoculation. The fourth generation meronts were observed in the crypts of the large intestine 144 - 153 h after inoculation. The gamogony took place in large intestine 167 h after inoculation. The mature oocysts were found 215 h after inoculation.