When pH was controlled during the growth of C. perfringens type C there was an increase in toxin but not in cells. The increases in toxin over that obtained at uncontrolled pH were 3-, 20-, 70-, and 4-fold, for alpha, beta, delta, and theta toxins respectively. pH control did not increase the yield of kappa toxin. Optimum pH was 6.7 for alpha, 7.5 for beta and theta, and 7.5–8.0 for delta. The maximum yields of toxins at optimum pH were 90 MLD of alpha, 100,000 MLD of beta, 2000 hemolytic units of delta, and 4000 hemolytic units of theta. Mu and nu toxins were not produced by the strain of type C used.