1. The effects of pirenzepine and N-methyl-scopolamine on the responses to ACh in the isolated rat vas deferens were studied. 2. Pirenzepine was inactive at the M2-ACh receptor. 3. N-methyl-scopolamine was a competitive antagonist (pA2 = 8.76) at M2-ACh receptor, alone or in the presence of pirenzepine. 4. Pirenzepine and N-methyl-scopolamine were both non-competitive antagonists at M1-ACh receptor. 5. The mixture of pirenzepine and N-methyl-scopolamine did not alter the type of antagonism demonstrated by each drug at the M1-ACh receptor.