Abstract In biotechnology, the interest in mass cultures of animal cells rises constantly; thus knowledge of the conditions influencing the cultures becomes important. Suspension cell cultures in bioreactors are subject to considerable shear forces, when stirring devices are employed. In order to get reliable data on the influence of shear forces on proliferation and antibody production of hybridoma cells, we tested cells, producing monoclonal antibodies against mitochondrial creatine kinase (Mi-CK), under laminar flow conditions in a rotating viscosimeter. Flow conditions in the annular gap were characterized by measuring the speed of revolution of the inner cylinder and the torque. From these data the shear stress could be determined. To confirm the laminar flow condition the velocity profile was determined by laser Doppler anemometry (LDA). After exposure to shear stress, cells were tested for viability, growth rate, antibody production as well as for the glucose uptake and lactate production rates. The data showed that cell death increases as a function of shear stress. The cells, remaining viable after exposure to shear stress showed growth and production rates similar to untreated cells.