Herbal medicines have been utilized to treat a variety of diseases, including cancer. Several species of the family rubiaceae have been reported to have antitumor activity. In this study, we report the cytotoxicity and antitumor activity exhibited dy the methanol extracts prepared from Rubia radix (RRME), Uncaria gambir (UGME) and Oldenlandia diffusa (ODME) (family: Rubiaceae) against human promyleloid leukemia cell line, HL-60. The cytotoxicity of RRME (2~20 ${mu}g/ml$), UGME (20~200 ${mu}g/ml$) and ODME (20~200 ${mu}g/ml$) were assessed dy the MTT reduction assay. IC50 values for RRME, UGME and ODME were 11.0, 99.5 and 106.1 ${mu}g/ml$, respectively. When the HL-60 cells were treated with RRME (10 ${mu}g/ml$), UGME (120 ${mu}g/ml$) and ODME (140 ${mu}g/ml$) for 24 h, several apoptotic characteristics such as DNA fragmentation and morphologic changes were observed. Furthermore, flow cytometric analysis was peformed to determine the percent of apoptotic cells. The poupulation of sub-G1 hypodiploid cells was increased 37.49% in RRME treatment, 12.49% in UGME treatment and 7.21% in ODME treatment compared with untreated control cells (2.64%). To further confirm apoptotic cell death, we assayed caspase-3, -8 and -9 activities in RRME, UGME and ODME-treated cells. After treatment of RRME, UGME and ODME for 12 h, caspase-3, -8 and -9 activities significantly increased.compared to untreated control cells. These results show that RRME, UGME and ODME induced apoptotic cell death in HL-60 cells and may have a possibility of potential antitumor activities.