In the present study the growth and MAb (monoclonal antibody) production of a mouse x mouse hybridoma cell producing anti-digoxin MAb was evaluated. The hybridoma cells entrapped within the support matrix Fibra-Cel were cultured in batch and continuous mode following special protocols. Cell-culture studies were performed in a 1-litre spinner basket containing 3 g.litre-1 support matrix. Batch culture was operated with the cell density of 42x10(6) cells. During the 7 days of culture, the medium was sampled daily in order to assess glucose and MAb concentrations and the lactate dehydrogenase released into the culture medium. After a culture period of 72 h, the cell density and MAb concentration were found to be 10.4x10(7) cells/3 g of NWPF (non-woven polyester fibre) discs and 250 microg/ml respectively. This yield gradually decreased to 0.55x10(6) cells/3 g of packaging material and 60 microg/ml respectively at the end of the batch culture. In the continuous-culture studies, the batch culture was initially operated for 64.5 h and then continuous flow was started at the dilution rates of 0.15, 0.2, 0.25 and 0.3 day-1 and finally stabilized at 0.25 day-1 within 288 h (12 days). The MAb concentration at steady state was found to be 116-120 microg/day per ml, and the yield of operation was 62.5 mg/day per ml, which was 3.5 times higher than that of batch culture. In conclusion, a packed-bed bioreactor with the support matrix Fibra-Cel, operated in continuous-feeding mode, is more efficient for large-scale MAb production than a batch culture. On the other hand, by using a continuous-culture system, a better supply of nutrients and removal of inhibitory metabolites and proteolytic enzymes was obtained.