A study was undertaken with the objective to find out whether a reliable transmission index could be established by a simple peptide ELISA. This would be important to evaluate the success of the bioenvironmental malaria control programmes implemented in endemic areas like the Haldwani and Shankargarh districts of Uttar Pradesh, India. We have estimated antimalarial antibodies against three synthetic peptides derived from blood stage antigens of Plasmodium falciparum and against P. falciparum crude antigen by enzyme-linked immunosorbent assay (ELISA), in children and adults. We have found that while all the peptides react with serum antibodies, as does the whole crude blood stage antigen, a nonapeptide from RESA antigen gave the most uniform results. Our results suggest that synthetic peptides, which are easy to obtain and can be fully characterized, may offer a simple way to measure malaria endemicity.