Batch cultures of mouse-mouse hybridoma cell lines were carried out and their growth and production kinetics investigated. Three main cell specific production patterns (expressed as pg IgG/cell x hour) were found, which can be used as a classification system for hybridoma cell lines (groups I-III). Cells showing the highest IgG-production at the beginning of the batch culture (during the lag and the onset of the log-phase) were classified as either group I and II. The difference was that cell lines of group II showed a second high cell specific production at the onset of the stationary and death phases. Cell lines of group III had a quite constant production of antibodies during their growth; but IgG secretion completely stopped after the beginning of the stationary phase. The implications of these three production patterns on the design of a production process are discussed.