CKBM is a product composed of natural ingredients and had been shown to possess certain anti-cancer effects in vitro and in vivo. The aim of the present study is to analyze the chemosensitivity in the treatment of primary colon, breast, gastric and bladder cancer cells by CKBM. A total of 77 patients with cancers of breast, colon, stomach or bladder were included in the present study. Primary cancer cells were isolated from the surgical removed tumors and treated with various dosages of CKBM for 5 days. ATP is then extracted and measured by luminescence assay. CKBM treatment inhibited primary colon, breast, gastric and bladder cancer growth dose-dependently. The IC values were smaller from tumor cells at early stages, when compared with the ones at later stages. The present study strongly indicated that CKBM exerted cytotoxic effect on primary cancer cells.