A hybridoma producing monoclonal antibody (MAb) specific for enrofloxacin was cultivated in a 2-L stirred-tank bioreactor in various modes and the performances of each mode were compared. In batch mode, a maximum viable cell and MAb concentration of 9.21 × 10^(5) cells mL^(-1) and 67.3 mg L^(-1), respectively, were obtained. When the hybridoma was cultivated in a fed-batch culture with the addition of specific nutrients, no improvement in either the viable cell number or MAb concentration was observed. On the other hand, an increase in the production of toxic metabolites, i.e. ammonia and lactate, was observed with growth inhibition of the hybridoma cells occurring at ammonia and lactate concentrations of 2.0 mM and 2.0 g L^(-1), respectively. However, the best performance of hybridoma cultivation was achieved in a perfusion culture mode using a spin filter, which was installed in the stirred-tank reactor as a cell retention device with a perfusion rate of 0.80 vvd. Under these conditions a steady viable cell concentration of 1.57 × 10^(6) cells mL^(-1) was obtained within five days with an overall productivity and yield of 73.7 mg L^(-1) d^(-1) and 61.4 mg d^(-1), respectively, which was a significant increase over that attained with the batch process.