The present study aimed to investigate the relationship between moral intelligence of high school girls and boys and their attitude toward pre-marital relationships. In this survey, 384 Mashhadi high school girls and boys, aged between 15 and 19, were randomly selected. The instrumentation comprised Moral Intelligence Scale (Lennick & Kiel, 2005) as well as the Scale of Attitude toward Pre-Marital Relationships (Shafiabadi & Sharifi). The collected data were analyzed via independent t-test and the Pearson correlation coefficient. The mean of moral intelligence scores and that of the attitude toward pre-marital relationships were 3.5 and 2.5, respectively. Moreover, 46% of participants had pre-marital relationships while 54% did not have such relations. More specifically, 58% of the boys and 34% of the girls had pre-marital relationships. The results showed that there was a significant negative relationship between the students’ moral intelligence and their attitude toward having pre-marital relationships. In other words, the higher the students’ moral intelligence, the lower their tendency to having pre-marital relationships. In addition, the students’ mean attitudes scores were different among male and female ones and the boys obtained higher mean. Nevertheless, there was no statistically significant relationship between moral intelligence and gender, and the boys and girls had a similar moral intelligence.