Delta(9)-Tetrahydrocannabinol (Delta(9)-THC) shows its effects by activating cannabinoid receptors which are on some tissues and neurons. Cannabinoid systems have role on cell proliferation and development of neurons. Furthermore, it is interesting that cannabinoid system and rho/rho-kinase signalization pathway, which have important role on cell development and proliferation, may have role on neuron proliferation and development together. Thus, a study is planned to investigate rhoA and rho-kinase enzyme expressions and their activities in the brain of chronic Delta(9)-THC treated mice. One group of mice are treated with Delta(9)-THC once to see effects of acute treatment. Another group of mice are treated with Delta(9)-THC three times per day for one month. After this period, rhoA and rho-kinase enzyme expressions and their activities in mice brains are analyzed by ELISA method. Chronic administration of Delta(9)-THC decreased the expression of rhoA while acute treatment has no meaningful effect on it. Administration of Delta(9)-THC did not affect expression of rho-kinase on both chronic and acute treatment. Administration of Delta(9)-THC increased rho-kinase activity on both chronic and acute treatment, however, chronic treatment decreased its activity with respect to acute treatment. This study showed that chronic Delta(9)-THC treatment down-regulated rhoA expression and did not change the expression level of rho-kinase which is downstream effector of rhoA. However, it elevated the rho-kinase activity. Delta(9)-THC induced down-regulation of rhoA may cause elevation of cypin expression and may have benefit on cypin related diseases. Furthermore, use of rho-kinase inhibitors and Delta(9)-THC together can be useful on rho-kinase related diseases. (C) 2017 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.