The authors report the establishment of a human myeloma cell line--KM-2R--and its preliminary use in human-human hybridoma research. KM-2R cells are resistant to both 6-TG and ouabain. Their doubling time is about 30 h. They have a modal chromosome number of 81-85. Using ELISA and immunodiffusion techniques, gamma-heavy and kappa-light chains were detected in the concentrated cell culture supernatant. KM-2R cells are sensitive to HAT medium. When fusing with normal human spleen cells, tonsil cells, and B lymphoblasts transformed by EB virus, fusion frequencies of 20-60% resulted.