The use of the severe combined immunodeficient mouse (SCID), CB-17/Icr//Imd-SCID, was investigated for the production of human hybridoma ascites containing human antibody. Human-human hybridomas, generated from the fusion of lymphocytes isolated from regional draining lymph nodes of cancer patients with the SHFP-1 fusion partner, were injected i.p. at various cell concentrations into pristane-primed SCID mice. Ascites growth was typically observed at 7-14 days postinoculation. No significant differences in ascites yield or production were observed between IgG- and IgM-secreting hybridomas. Yields of immunoreactive human immunoglobulin ranged from approximately 0.5 to 3 mg/ml of harvested ascites. The ease and relatively low cost suggest that the use of SCID mice is preferred over conventional and costly large-scale industrial procedures.