The exposure of human lymphoid leukemia Molt 4B cells to diol- and triol-types of phytol which were synthesized and identified by Mass, and 1H- and 13C-NMR, led to both growth inhibition and induction of programmed cell death (apoptosis). Morphological changes showing apoptotic bodies were observed in the Molt 4B cells treated with diol- and triol-types of phytol. The fragmentations of DNA by the diol- and triol-types of phytol to oligonucleosomal-sized fragments, that is a characteristic of apoptosis, were observed to be both concentration- and time-dependent. These findings suggest that growth inhibition of Molt 4B cells by the diol- and triol-types of phytol results from the induction of apoptosis in the leukemic cells.