The present study aimed to examine the relationship between coaches' leadership styles and some personal characteristics with group cohesion and team success. Out of 135 athletes who participated in female volleyball championships of Azad universities, 116 athletes (86%) completed the demographic questionnaire, leadership scale for sport (LSS) and group environment questionnaire (GEQ). The LSS contained 40 items that measured five dimensions of leadership behaviors and the GEQ with 18 items assessed two dimensions of group cohesion. Cronbach’s alpha coefficient was used to examine the internal reliability of LSS (r = 0.91) and GEQ (r = 0.71). Data were analyzed with parametric tests at P?0.05. Results showed a positive significant relationship between coaches' behaviors of training and instruction, social support and positive feedback with group cohesion. There was no significant relationship between democratic and autocratic behaviors with group cohesion. Comparison of coaches' leadership styles demonstrated that coaches exhibited higher training and instruction and lower autocratic behavior. In addition, findings showed no significant relationship between group cohesion and team success and the coaches of successful teams exhibited higher training and instruction behaviors. Also, there was no significant relationship between age of players and age of coaches with coaching behaviors. In summary, the effect of coaching behaviors on group cohesion and team success obviously demonstrated the importance of using the appropriate leadership styles.