A total of 819 Indian inhabitants (from 6 months to over 60 years of age) in an oil-palm plantation in West Malaysia was examined for soil-transmitted helminthiases using the brine flotation and Kato thick smear techniques. Half (51.0%) of the inhabitants were found to be infected (33.9% had Ascaris lumbricoides; 36.4% had Trichuris trichiura and 15.6% had Necator americanus). Soil-transmitted helminthiases (both single and mixed infections) were significantly more common among children and young adults from 6 months to 20 years of age where 67.1% (range: 64.7-70.3%) of this age group were infected. The infection rate declined to about 25% or less among elderly people over 50 years of age. Trichuris trichiura was the commonest helminth observed--both as single and mixed infections--and Trichuris mixed with Ascaris was the commonest type of double infection reported. However, there were no significant differences in the distribution of the types of single and double infections among inhabitants of different age groups, nor were there any significant differences in the distribution of soil-transmitted helminthiases among male and female inhabitants. The socioeconomic, environmental and cultural factors contributing to persistently high rates of infection with soil-transmitted helminths among plantation inhabitants are discussed.