Entomological, parasitological and serological surveys were conducted between October 1989 and November 1990 in 27 villages (population 33,250) belonging to three topographically different areas of district Allahabad, viz. Gangapar, Doaba and Yamunapar. A good correlation existed in all the three areas between malaria incidence vis-a-vis An. culicifacies sibling species composition and malaria antibodies titre in the populations. In Gangapar and Doaba villages, An. culicifacies densities were low and the proportions of vector species A and C were much less than that of species B, the non-vector species. Low endemicity of malaria was supported by low antibody titres observed in the population. In contrast, in Yamunapar villages An. culicifacies densities were high, species A and C together were almost equal to species B, and malaria incidence as well as antibody titre were high. Based on these observations, district Allahabad, Uttar Pradesh, could be divided into two zones, low malaria transmission zone--Gangapar and Doaba areas and high malaria transmission zone--Yamunapar area.