Life cycle of Eimeria coecicola was studied in experimentally infected rabbits by light microscopy and by transmission and scanning electron microscopy. First and second generation meronts developed in the vermiform appendix; third and fourth generation meronts were located in the epithelium of the ileum. Gametogony developed again in the vermiform appendix. The prepatent period was 9 days. New data were obtained by the study of asexual reproduction. First generation meronts were first observed 4 days post infection (DPI), which is relatively late in comparison with other species of rabbit coccidia. Sporozoites were found in lymphatic follicles of the vermiform appendix at 4 DPI by transmission electron microscopy. This suggests, together with selective location of first generation meronts in the epithelium adjacent to these follicles, that major part of sporozoites enter the epithelium cells through lymphatic follicles and not through the lumen of the vermiform appendix. The process of development of first generation merozoites is similar to endodyogeny. The differences are in formation of apical parts of daughter merozoites which is not coincidental with nuclear division and in formation of the outer membrane of pellicle which arises within the mother cell. Some first generation merozoites have 2-3 nuclei, second and fourth generation merozoites are only uninucleate, while third generation merozoites are only multinucleate. We found that further merozoites are formed in multinucleate third generation merozoites by endopolygeny.