1. (1) A survey of north-west Malayan fishing villages suggests that sea-snake bite is much more common than has hitherto been realized. 2. (2) Biology of sea-snakes is described with a brief account of them in captivity. 3. (3) Venom yields of several sea-snake species are reported, and available information on toxicity quoted. 4. (4) The pathological changes in subjects of sea-snake bite are described, and other aspects of basic toxicology considered in the light of relevant work. 5. (5) The treatment of neurotoxic snake poisoning is critically reviewed. The prevention of sea-snake bite is briefly discussed. 6. (6) A new theory is postulated to account for the apparently large number of sea-snake bites which do not cause serious signs of poisoning. 7. (7) The need for further clinical and laboratory research is mentioned.