The study was aimed at detecting the effects of Baycox and Chitosan on the development of coccidiosis on a broiler farm. The study involved 80 six-week-old-broiler chickens divided into two equal groups. Each group was divided into four subgroups: control (I); Baycox-treated (II); Chitosan treated (III); and Baycox- and Chitosan-treated (IV). Baycox was applied for 2 d in a concentration of 25 ppm in drinking water. Chitosan was used for 6 d at a daily dose of 0.6 g/bird. The coccidial infection intensity was expressed as the intestinal mean total lesion score (MTLS) and coccidial index. The coccidial infection intensity was determined twice within 6 d following the administration of each drug. The combined application of Baycox and Chitosan produced the best results: neither pathological changes nor the presence of coccidial oocysts were observed in the intestines. The results of separate administration of Baycox and Chitosan were comparable; the MTLS values were 0.35 and 0.4, respectively.