In July and October, 1980,larval collections were carried out to clarify mosquito fauna and their habitats around the human dwellings at Ishigakijima and Iriomotejima. The results are summarized as follows : 1. In total, the following 15 species of 5 genera were collected : Anopheles sinensis, Tp. b. yaeyamensis, Ae. a. okinawanus, Ae. watasei, Ae. albopictus, Ae. f. miyarai, Ae. riversi, Ar. subalbatus, Cx. halifaxii, Cx. fuscanus, Cx. okinawae, Cx. bicornatus, Cx. ryukyensis, Cx. p. quinquefasciatus and Cx. tritaeniorhynchus. Among them, Ae. albopictus was most dominant, making up 73 to 74% of the total catch in both islands. Ae. aegypti which was recorded frequently before in these islands, was not found in the present survey. 2. The predominant breeding sites of the mosquito were tin cans (31-32% of total sites), small earthen jars (23-24%), plastic containers and tires.