The effects of beryllium on cultured cells were investigated. Three cell-lines (HeLa-S3, Vero, HEL-R66) were used in these experiments and they were cultured in Eagle's MEM plus 5 or 10% FBS (Fetal Bovine Serum) containing beryllium in various concentrations. HeLa cells or Vero cells were able to grow in the medium with 10 μg Be/ml (1.1 mM). On the other hand, the growth of HEL cells were strongly inhibited, even when cultured in the medium with 1 μg Be/ml (1.1×10^-1 mM) and the number of living cells showed markedly low level as compared to that of the control samples cultured in the medium without beryllium. The cytotoxic effects of beryllium on these cells, which were cultured for three days in the medium with beryllium, were observed. None of cytotoxic effects were found on HeLa cells cultured with 0.5 μg/ml (5.5×10^-2 mM) and on Vero cells cultured with 0.05 μg Be/ml (5.5×10^-3 mM), while HEL cells received cytotoxic effects even when cultured in the medium containing 0.05 μg Be/ml (5.5×10^-3 mM), and these effects on the cells appeared strong when cultured in the medium without FBS. It was revealed from these experiments that HEL cells are very sensitive in terms of toxic effects of beryllium. Therefore, there cells can be used for the toxicological study on low level concentrations of the metal.