This work investigated the effects of dimethyl suffoxide (DMSO) on protein productivity and metabolism in the culture of recombinant CHO cells to produce hepatitis B surface antigen (HBsAa). In the presence of 1.5% DMSO, the specific RBsA- production rate increased by 2.7-fold in despite of cell growth inhibition. DMSO decreased significantly the specific rates of nutrient consumption and metabolite production, and also arrested CHO cells at G1 phase of cell cycle. The cell proportion of G1 phase increased to 68.3% in 1.5% DMSO from 57.7% in control. Intracellular HBsAg accumulation increased gradually and reached 982 mg/l in the cells cultured with 1.5% DMSO in 48 h, which was 15-fold higher than the control. However, extracellular HBsAg increased observably after an adaptive phase of 48 It. The results show that DMSO is a useful additive for inducing protein production in CHO cell cultures. (c) 2005 Published by Elsevier Ltd.