Abstract: In order to investigate the effects of second crop cultivation on growth yield and yield components of rice, a field experiment was conducted at Rice Research Institute of Iran-Deputy of Mazandaran during 2005 and 2006. Tarom as a traditional variety and Fajr as a improve variety were used in this research. Clover, Potato, Canola and Cabbage were used as a second crop in rotation with rice. Second crop cultivation had not significant effect on yield and yield components of rice variety but second crop cultivation had significant effect on plant height at 1% probability level. Results indicated that rice varieties had different reaction to second crop cultivation. According to results, Rice-clover-Rice and Rice-fallow-Rice rotations systems for the best performance of rice yield in North of Iran`s paddy fields were recommended.