Cell growth rate and production of monoclonal antibody (MAb) of hybridoma cells producing anti-human chorionic gonadotropin (hCG) MAb have been used as investigation criteria in double-mouthed rolling bottle (DMRB). Compared with T-flask cell culture, both of the cell number and MAb production increased by approximately 42.5% when the medium was supplemented with 5% fetal calf serum (FCS) and DMRB rotated at 2 turns per minute. Yield of MAb was experimentally related to the number of viable cells. Interestingly, MAb yield was four times as high as that cultured in T-flask in the first 24 hours, and about 75% yield of total MAb was secreted by 48 hours during the culture. It appears that the promoted cell growth and MAb yield are resulted from the three-dimensional growth of hybridoma cells under a suitably revolving condition.