Two monoclonal antibodiesWuchereria bancrofti E 33 andWuchereria bancrofli E 34 raised againstWuchereria bancrofti microfilarial excretory-secretory antigens were studied for their diagnostic utility.Wuchereria bancrofti E 34 monoclonal antibody was found to be relatively specific and sensitive in detection of circulating filarial antigen. WhenWuchereria bancrofti E 34 monoclonal antibody was used alongwith immunoglobulin G fraction of human filarial serum immunoglobulins in double antibody sandwich enzyme linked immunosorbent assay. 68% of microfilaraemic sera (26 out of 38). 12% of clinical filarial sera (3 out of 25), 13% endemic normal sera (2 out of 15) and none of the 20 non-endemic normal sera showed the presence of filarial antigen. The filarial antigen detected byWuchereria bancrofti E 34 monoclonal antibody in double antibody sandwich enzyme linked immunosorbent assay is possibly associated with the active stage (microfilaraemia) of infection.