Dissertation (MSc Nursing Mental Health)Background: Substance use in young people is significant public health concerns which need to be understood and addressed. Young adolescent is a period when substance use typically starts and patterns become established (NDARC, 2016). Objective: The study was aimed at determining predictors of substance use among undergraduate university students in Dodoma Municipal. Method: A cross-sectional study design was employed involving undergraduate university students aged from18 years and above. Risk factors of substance use were measured by self-administered questionnaire, known as the Substance Use Questionnaire. Simple and systematic randomly sampling techniques were used to select participants. Data were analyzed by SPSS version 20. Chi-square test and logistic regression were used in the analysis. Results: A total of386questionnaires were completely filled by participants. Proportion of male was 64.5% and that of female was 35.5%. The mean age was 24.5 years with a standard deviation of 3.24. Up to 43% of the participants found to be currently using one or more substances, and the commonest substance used was alcohol (48.2%) followed by cigarette (13%) cannabis (7.8%), khat (5.4%), and sedatives/tranquilizer (4.7%). Multivariate logistic regression has shown that, compared with students residing in university hostels those who stayed in their home (AOR=0.07, CI: 0.01, 0.70) or rented rooms (AOR=0.13, CI: 0.04, 0.45) had significantly lower chance of drinking alcohol. Students with friends who drank alcohol had higher odds of drinking alcohol (AOR=17.9, CI: 4.46, 71.82). Male students were significantly having a higher prevalence of cigarette smoking than female students (AOR=0.95, CI: 1.24, 12.54). Having friends who used cannabis was significantly associated with an increase in the chance of using cannabis (AOR=15.36, CI: 3.82, 61.71). Cigarette smokers had about 6 times more odds of using khat than that of non-smokers (AOR=6.03, CI: 1.66, 21.85). Conclusion: This study has shown a high prevalence of substance use among university students in Dodoma Municipal, with the most commonly used substances being alcohol, cigarettes, and cannabis. Male sex, peer pressure, low social economic status and living in the university hostels showed to have a significant relationship with substance use