An anti-hepatitis A virus (HAV)-specific immunoglobulin M capture enzyme-linked immunosorbent assay (anti-HAV IgM ELISA) kit was re-designed for laboratory use and compared with a commercial anti-HAV IgM detection system using 58 serum samples collected from patients, vaccines, and healthy individuals. Because concordance between the two systems was high (r = 0.93, P < 0.05), 19 sets of serum and fecal samples obtained from individuals exposed to an HAV outbreak were also examined. Serum levels of anti-HAV IgM were determined using the in-house ELISA kit and the HAV genome in fecal samples was detected using the polymerase chain reaction (PCR). Among the 19 sets of sample, 14 were positive for both anti-HAV IgM and the HAV genome. All of those whose serum samples were anti-HAV IgM negative were also negative for the HAV genome in fecal samples. The results of the in-house IgM ELISA were consistent with those of the HAV genome detected by PCR and with the commercial IgM ELISA. The in-house anti-HAV IgM ELISA kit was therefore proven suitable for laboratory use and applicable to epidemiological studies of HAV infection.