Seven villages in Central Sulawesi were surveyed in September 1971 and finger blood samples from 3,658 persons examined for microfilariae. Periodic, nocturnal Brugia malayi was endemic in all seven villages with microfilarial rates (Mf-rate) of 10-42% (av. 25%). The median microfilarial density (MfD50) averaged 5.4 and varied from 0.8 to 9.4 microfilariae per 20 microliter of blood. Males had higher Mf-rate and MfD50 value than females and in males Mf-rates and MfD50 values increased with age. In the female population, however, neither Mf-rates or MfD50 values varied significantly with age. Clinical manifestations of filariasis were found in 12% of 2,412 persons examined and only 2% had elephantiasis. Clinical signs of disease with the exception of elephantiasis, showed good correlations with Mf-rates but not with MfD50 values. Transmigrants experienced clinical manifestations of filariasis earlier and more often than the indigenous population.