A comprehensive approach was taken toward the quantitative study of hybridoma growth and antibody production. A fractional factorial experimental method was used to identify important variables and variable interactions affecting hybridoma behavior. The variables studied include temperature, pH, dissolved oxygen, glucose, glutamine, base medium, serum, lactate, and ammonium. The growth rate was strongly affected by the levels of dissolved oxygen, pH, temperature, and base medium. Interactions between temperature, pH, and dissolved oxygen were important. The optimal pH for growth depends upon the temperature and dissolved oxygen concentration. In general, growth was fastest at low dissolved oxygen levels. The growth rate was very sensitive to low concentrations of base medium, but was relatively insensitive to the serum concentration at levels above 2.5%. Antibody production was stimulated by high concentrations of base medium and serum and inhibited by ammonium and lactate. Antibody production increased linearly with serum concentration. In general, conditions that favored a high growth rate also favored a high specific rate of antibody production. The functional dependencies of antibody production on base medium and ammonium were similar to those for cell growth; however, antibody production and cell growth exhibited different dependencies on serum. Mathematical descriptions of cell growth and antibody production were developed. These experimental results have significant implications for the optimization of hybridoma growth in bioreactors.