Objective: We investigated the effects of fusidic acid (FA) on human cervical, thyroid, and breast carcinoma cell lines to determine the potential usefulness of FA in cancer treatment. Methods: Six cancer cell lines (cervical cancer: Caski, HeLa; thyroid cancer: 8505C, TPC1; and breast cancer: MCF-7, MDA-MB-231) were treated with FA. Furthermore the changes in cell growth, cell cycle duration, and extent of apoptosis were analyzed. Results: After FA treatment, the cancer cells showed a decrease in growth rate. In the cell death assay, the cell populations were similar in each cell type after treatment with FA, indicating that growth inhibition by FA was not related to the induction of apoptosis. FA induced cell cycle arrest at a dose that inhibited growth rate, which varied in different cell types. G0/G1 phase arrest occurs in breast cancer, S phase arrest in 8505C thyroid cancer, and G2/M phase arrest in cervical cancer. These results indicate that FA reduces growth rates by inducing cell cycle arrest. Conclusion FA treatment can interfere with cell proliferation by inducing cell cycle arrest in human cervical, thyroid, and breast carcinoma cell lines. Thus, FA can be useful in treating human cervical, thyroid, and breast carcinomas.