The results of the present study indicated that nimbolide induced the G2/M phase cell cycle arrest in bladder cancer cells via Chk2-Cdc25c-Cdc2/cyclin B1-Wee1 axis and Chk2-p21WAF1-Cdc2/cyclin B1-Wee1 axis. This evidence concerns the gene CHEK2 and urinary bladder carcinoma.