An epidemiological study of the outbreak of paralytic poliomyelitis that occurred in 1962 is given. A total of 1,810 paralytic cases was reported from all parts of the island with a case fatality rate of 8.8%. The areas with very high morbidity were the health areas of Vavuniya, Jaffna, Colombo and Batticaloa. The outbreak, which commenced in February, reached its peak in various parts of the island during the months of March, April, May, June, July, August and September. The original focus of infection was in Colombo. Laboratory studies showed that the virus responsible was poliovirus type 1. The disease affected mostly children of the very low socio-economic group. An oral vaccination program with Sabin live oral vaccine (trivalent) was started in March in Colombo and extended to other areas when vaccine became available in large quantities. While the effects are not analysed here, in areas where vaccination was carried out rapidly, covering a large percentage of the susceptible group, a marked reduction in cases was seen, as in Colombo and Jaffna.