Chlorocholine chloride (CCC) inhibits neuromuscular transduction of excitation and, consequently, leads to respiratory arrest in cases of acute intoxication. An account is given of the relationships between neuromuscularly blocking activity and acute toxicity of CCC. Several animal species and pharmacological models are used to produce evidence to the effect that CCC-caused inhibition of neuromuscular transmission of excitation is characterised by parameters typical of block due to depolarisation. The differentiated sensitivity of species to depolarising neuromuscular blockers is thought to be the decisive cause of species differences regarding acute toxicity of CCC. Conclusions are discussed which may be derived from the above findings regarding acute CCC toxicity to man and agricultural animal.