The clinical balantidiosis if not treated can assume a fatal form leading to heavy loss was shown in control group. This together with our previous observations proves that balantidiosis is not necessarily a benign or harmless parasite as mentioned by Levine (1973). Our observations support the view of Almejew (1963) who found acute balantidian dysentery fatal in certain cases. Terramycin was able to eliminate the infection in 14 out of 20 cases and reduced it from +++ to + in 6 cases. This antibalantidian activity combined with its well known bacteriostatic and bactericidal action against many microorganisms may prove