An experiment was conducted for 8 weeks to study therapeutic effects of six coccidiostats with 420 broiler chicks of Starbro strain artificially inoculated with coccidia. The results obtained are summarized as follow. 1. Although D group received $quot;Coyden 25$quot; appeared to be nearly free from coccidial symptom, the rest were seriously stressed in appearance, so as unmedicated group. 2. Medicated groups gained slightly more body weight during the first three weeks before inoculation than control group, but the differences were not significant. 3. The greatest total gain throughout the entire experimental period was achieved by Coyden fed group (p$lt;.01), while the others gained insignificantly more than control group, except for groups B and C which showed no difference from control group. 4. Feed intake was also the greatest for birds medicated with Coyden. And in terms of feed efficiency, no significant difference was detected among the treatments. 5. It is concluded that Coyden has the most powerful effect against coccidiosis out of six coccidiostats tested. Pigmentation of shank and skin of broiler could also be improved by the use of Coyden.