The development of immunodiagnostic tests (IDTs) for bancroftian filariasis must be aimed at defined objectives, such as the determination of exposure rates, the detection of microfilaraemia and the diagnosis of clinical filariasis. Assays for both antibody and antigen detection are necessary. Antigen determination may be more appropriate in the detection of microfilaraemia, but for clinical filariasis, antibody determination may prove more useful. The microfilarial surface antigens are very good candidates for this purpose. Determination of antibody to larval antigens may be the best way of establishing exposure rates for epidemiological purposes. An important prerequisite for IDT development is the characterization of antigens at epitope level. Sharing of antigen epitopes with host antigens could be a major limitation in IDT development. An understanding of the parasitological and immunological background of the endemic locality is also necessary. It is recommended that all IDTs are evaluated in follow-up case studies.