Annona muricata, commonly known as soursop, contains annonacin, acetogenin, and polyphenol which are known to have chemopreventive effects on cancer. In this study, we tend to evaluate the apoptosis-inducing effect of soursop (Annona muricata) leaf extract on the colorectal cancer cell line COLO-205 through the activities of caspase-3 which is a marker of cell apoptosis. Cell cultures were incubated with soursop leaf with a concentration of 10 μg/ml and then compared with those of the incubated positive control leucovorin 10 μg/ml and placebo as a negative control. The apoptotic activity of caspase-3 was measured with ELISA. After the administration of each treatment in the colorectal cancer cell line COLO-205, the expression of caspase-3 activity was 1422 ng/ml after incubation with the extract of Annona muricata leaves, 1373 ng/ml after the administration of leucovorin, and 1297 ng/ml in the one with placebo. Annona muricata leaf extract elevated caspase-3 by 1.09 times compared to that of the pure cell line. Annona muricata leaf extract had a higher value of caspase-3 activity than leucovorin and placebo in the COLO-205 colorectal cancer cell line. These results may suggest that Annona muricata leaf extract had anticancer properties by enhancing caspase-3 activity which is a proapoptotic marker.