Coccidia isolated from 16 poultry farms in Czechoslovakia, were passaged once in chickens and then identified by microscopic examination of stages in different regions of infected gut, measurement of the oocysts and electrophoresis of lactate dehydrogenase and glucose phosphate isomerase. Two or more species of Eimeria were present concurrently on 14 farms and there was no substantial difference in the species recovered from poultry kept on litter or in cages. The most common species identified were, in decreasing order: E. acervulina (15/16 farms), E. tenella (11), E. mitis (8), E. maxima (6), E. praecox (5), E. brunetti (4) and E. necatrix (1).