A nine month entomological and parasitological study was conducted between December 1991 and August 1992, at Kanchrapara, a town of the district North 24-Parganas, West Bengal. The town was found to be endemic for bancroftian filariasis. Microfilaria rate among the human population was 1.9 per cent (35 of 1200 persons). Average man hour density of C. quinquefasciatus was considerably high (31.10) and a higher vector prevalence was seen in summer. The infection and infectivity rates of the natural population of the vector were 2.3 and 0.28 per cent respectively. 9.2 and 1.7 per cent of the human habitations were found to contain infected and infective C. quinquefasciatus. Both infection and infectivity rates were higher during the rainy season than the other seasons.