The effects of hydrostatic pressure on hybridoma cell metabolism were investigated. In cell cultures grown at various constant hydrostatic pressures between 0.1 and 0.9 MPa, little variation was observed in either cell growth or the specific glucose consumption rates at different pressures. However, the rate of conversion from glucose to lactate decreased from 89 to 83%, while the specific glutamine consumption rate increased from 1.07 to 1.29 x 10(-13) mol/cell/h between the lowest and highest pressures. The specific production rate of monoclonal antibody (MAb) rose from 4.5 to 5.6 x 10(-13) g/cell/h in proportion to the pressure increase. The main factor affecting the conversion rate was not the hydrostatic pressure during cell propagation, but rather the hydrostatic pressure at which metabolism occurred. The specific glutamine consumption and MAb production Fates were influenced by the hydrostatic pressure in both the growth and production phases of the cultivation.