A horizontal study of the prevalence of Ascaris infection was carried out on the total population of Okpo village near Rangoon, Burma, where a similar study had been conducted 13 years earlier. Ascaris eggs in faeces were counted after treatment with levamisole on a random sample of 50% of the infected population to give information to the numbers of epg of stool, the mean worm burden per host and the distribution of worms in the community. The information on prevalence is compared with that of the previous survey. Various population parameters of Ascaris were calculated to estimate the transmission dynamics of A. lumbricoides. In addition, chemotherapeutic regimes, assessed on the proportion of the human population to be treated and the time interval between treatments, are proposed to reduce transmission below a critical threshold. The findings are compared with those of other studies and the probable mode of occurrence and maintenance of Ascaris infection in Okpo village are discussed.