We developed a useful method for the establishment of stable cell lines producing human monoclonal anti-DNA antibody by in vitro Epstein-Barr virus infection. The practical limitation for the cloning was overcome by 2 procedures. One was a microculture system using a small number of the culture. Another was enrichment of anti-DNA producing cells at an early stage and prior to the cloning. The combination of these procedures allowed ready derivation of the cell lines secreting monoclonal anti-DNA antibody. Sixteen cell lines were cloned by utilizing colony formation methods in soft agarose. About 14–32 μg per ml of IgM with specific antibody activity were obtained in the supernatant of the cells. The antibody reacted with double-stranded and/or single-stranded DNA. These cells have been continuously producing the specific antibody for more than 3 years. We may extand this procedure for obtaining other autoantibodies, such as anti-T cell antibodies.