Effectiveness of the auto vaccine Dipervac prepared by the authors and containing toxoids alpha and beta of C. perfringens A and C in protecting calves against a toxic diarrhea was examined. The vaccine was used in pregnant cows at 7 and 2-3 weeks before parturition. The vaccine induced a high level of antitoxic antibodies (4-64 ai/ml for alpha and 8—64 ai/ml for beta toxin) without negative effects on immunized animals. Dipervac used in 375 cows on two farms with endemic toxic anaerobic calf diarrhea decreased losses of calves from 22.3% to 3.1%. Dipervac can be used in prophylaxis of diarrhea in calves induced by alpha and beta toxin of C. perfringens A and B.