The isolated Lake Lindu Valley of Central Sulawesi is the only reported Indonesian focus of oriental schistosomiasis. In April 1972 a parasitological survey involving over 1,400 people was conducted in the valley's four villages. Schistosoma japonicum infections were detected in 37.9% of all Lindu people by direct and formalin-ether concentration examinations of stools: 57.1% in Anca, 42.4% in Tomado, 30.0% in Langko, and 11.7% in Puroo. Peak prevalences of schistosomiasis were reached in the second decade of life and remained high thereafter among both male and female populations. Prevalences of other helminthic parasites are reported as follows: Hymenolepsis diminuta, <0.1%; Strongyloides stercoralis, 0.2%; Enterobius vermicularis, 0.8%; Trichuris trichiura, 8.8%; Ascaris lumbricoides, 15.2%; and hookworm (Necator americanus), 69.6%. No Echinostoma lindoense infection was detected. Intestinal protozoa including Entamoeba coli, Giardia lamblia, Endolimax nana, Entamoeba histolytica, Iodamoeba butschlii, Entamoeba hartmanni, and Chilomastix mesnili were also encountered. In blood smears collected from 1,348 people, Brugia malayi microfilariae were detected in 5.4% of the population, and Plasmodium vivax and Plasmodium falciparum in 2.5%. Filariasis was more frequent in older age groups, while most malaria infections were found in Lindu residents 10 years old or younger.