P-Aminobenzoic acid (PABA) reversed the inhibition of BCG by sulfathiazole, p-aminosalicylic acid, and p,p[image] -diaminodiphenylsulfone. p-Nitrobenzoic acid, p-nitro-N-(2_thiazolyl) benzenesulfonamide, and p, p[image]-dihydroxy-diphenylsulfone inhibition of BCG growth was not reversed by PABA.