Effects of electromagnetic fields (EMFs) on human cell lines were described in numerous studies, but still many questions remain unanswered. Our experiment was designed with the aim of studying the effects of EMFs on the metabolic activity of chondrocytes in vitro. Human chondrocyte in vitro cultures, cultured in medium supplemented with 20 % fetal calf serum, were exposed to static magnetic field (SMF) (intensity of 0.6 T) and pulsed electromagnetic fields (PEMF) (21.2 MHz period of 15 ms, burst duration of 2 ms, amplification 3 dBm (0.1 V) and maximum output of 250 W) continually for 72 h. After the exposure, viability was determined using the MTT test and compared with a nonexposed control culture. As compared to the control sample the exposure to SMF resulted in a statistically significant increase (p<0.001) in viability. However, the increase of viability after PEMF exposure was not significant. This could be due to the frequency dependent effect on human cells. The experiments demonstrated that magnetic fields, using the above parameters, have a positive effect on the viability of human chondrocytes cultured in vitro., Š. Štolfa, M. Škorvánek, P. Štolfa, J. Rosocha, G. Vaško, J. Sabo., and Obsahuje bibliografii