Sudan is one of the Islamic countries where extramarital sex is religiously forbidden and socially unacceptable. However, increasing numbers of university students become engaged in premarital sex practices, which increases their risk of contracting STIs, including HIV, and puts them into conflicts with their religious beliefs. As little is known about the motivations for abstinence from premarital sex, this study aimed to identify these psychosocial determinants. Using a cross-sectional design, a sample of 257 students between18 and 27 years old was recruited from randomly selected public and private universities in Khartoum. The participants filled out an online questionnaire based on the Integrated Change Model (ICM) to assess their beliefs and practices about abstinence from premarital sex. The analysis of variances (MANOVA) showed that the students who reported being sexually active differed significantly from abstainers in having more knowledge about HIV/AIDS, higher perception of susceptibility to HIV, more exposure to cues that made them think about sex and a more positive attitude towards premarital sex. The abstainers had a significantly more negative attitude towards premarital sex, higher self-efficacy to abstain from sex until marriage and perceived more peer support and norms favouring abstinence from sex until marriage. These findings suggest that promoting abstinence from sex until marriage among university students in Sudan, which aligns with the Sudanese religious values and social norms, requires health communication messages addressing these potential determinants. However, given that sexual encounters still may occur, health communication messages may profit from a more comprehensive approach by also addressing the need for condom use for those unwilling to refrain from sex.