Entomological and filariasis surveys were conducted simultaneously in a rural and an urban environment in West Bengal from September 1986 to August 1987. The aim of the surveys was to see if any correlation existed between the preferred biting site of Culex quinquefasciatus, the filarial vector, and the region of the body affected by clinical filariasis. Significantly more mosquitoes (> 55%) attacked the thighs, legs and feet of human volunteers than other sites on their bodies, whether the volunteers were indoors or outdoors, in rural or urban environments. Significantly more patients had clinical filariasis of these lower body parts than of the upper parts. The vector's preferred biting sites and the anatomical sites most affected by clinical filariasis were therefore the same.