Dimecamine is ganglion blocking agent. A slowly developing but moderate contracture of the chick biventer cervicis muscle was observed with 5x10-4M-dimecamine methiodide solution. A small reduction in the twitch response was also observed. Similar concentrations of dimecamine and pempidine produced only slowly developing and very small contractures. Dimecamine differs in neuromuscular-blocking activity from its corresponding quaternary metho-salts by a factor of less than two.