A new fluorescent immunoassay system (FIAX TM) has permitted development of a promising serologic test for amebiasis. The test is similar but far superior to the soluble antigen fluorescent antibody test. The main differences are the unique StiQ TM sampler and the flourometer itself. Quantitative results can be obtained from a single standard dilution of serum. The procedure is simple to perform, gives objective readings, and uses the proven principle of immunofluorescence. It is possible to test for different immunoglobulin classes and to use purified antigen prepared from axenically cultured Entamoeba histolytica. Conservation of reagents is comparable to microplate systems, and results are available in less than two hours. FIAX TM for amebiasis has demonstrated excellent discriminating power between amebic and nonamebic sera. Sensitivity is 100 percent for extra-intestinal amebiasis (33 sera), 90 percent for symptomatic intestinal amebiasis (20 sera), and 43 percent for asymptomatic amebiasis (seven sera). Specificity is 97 percent (158 sera).