The evaluation of the efficacy of anticoccidials requires floor pen experiments. With the method of infection suggested, i.e., the ingestion of an infecting feed during 5 consecutive days, it is easier to check animal contamination than with the "seeder birds" method, and the anticoccidial has a dual action, it protects the animals and at the same time diminishes they environmental contamination. The presence of a non experimentally infected group, treated by an anticoccidial drug makes it possible to judge normal performances of the animals. In addition to lesion scorings, serum coloration and hematocrits are excellent criteria to evaluate the incidence of parasitism. An experimental work plan is suggested.