Growth suppression and apoptosis inducing effect of (-)-epigallocatechin 3-gallate (EGCG) and (-)-epigallocatechin (EGC) were studied against human promyeolcytic leukemia, HL-60 cells. EGCG showed higher growth suppression against HL-60 cells than EGC. $IC_{50}$ values for EGCG were $60.0;{mu}M$ and EGC was $107.7;{mu}M$, respectively. Both EGCG and EGC induced apoptosis evidenced by nuclei fragmentation. Nuclear fragmentation was observed as a time-dependent manner and the extent of nuclear fragmentation was slightly higher in EGCG-treated cells than EGC-treated cells. The expression level of Bcl-2 was decreased and caspase-3 was activated by EGCG or EGC treatment. The extent in decrease of Bcl-2 and activation caspase-3 were more extensively occurred in EGCG-treated cells than in EGC-treated cells. These data corresponded to the growth suppression data. EGC showed no cytotoxicity to a normal V79-4 cell line and EGCG showed slight cytotoxicity at higher concentrations.