A popular polyherbal formulation prepared from five plants (PHF5) may have anticancer effects. However, there is a lack of adequate scientific evidence. We assessed the anticancer, antioxidant, and acute toxicity effects of PHF5. Cancer cells were treated with 0 to 300 μg/mL PHF5 extract. Established assays were used to assess cytotoxicity, apoptosis, and radical scavenging activities. In the acute toxicity study, mice were administered a single oral dose (2,000 mg/kg) of PHF5, and biochemical and histopathological parameters were assessed. The IC values of PHF5 on LoVo, HepG2, MCF-7, and MDA-MB 231 cells were 71.8, 64.8, 45.3, and 47.3 μg/mL, respectively. Fluorescence staining demonstrated that PHF5 induced MCF-7 cell apoptosis. After 48 h, the percentage of late apoptotic cells increased significantly compared with the control cells (74.16 ± 0.64 vs 3.7 ± 2.05, < 0.05). No mortality or behavioral alterations were observed in mice treated with a single dose (2,000 mg/kg) of PHF5, indicating that the LD value exceeded 2,000 mg/kg. However, histopathological changes were observed in the liver tissues. PHF5 has potential as a therapeutic agent for the treatment of human carcinoma. Further safety data will be necessary before clinical use.