The study explored the adoption and use of institutional repositories among postgraduate students in Muhimbili University of Health and Allied Sciences and Sokoine University of Agriculture. This study applied a mixed methods descriptive research design employing qualitative and quantitative methods. Interviews and questionnaires were used to collect data from respondents. Simple random sampling was used to select 55 respondents. Key findings showed 48 (87.3%) respondents were aware of institutional repositories. However, 21 (38.2%) were only moderately aware. Findings indicate low awareness of institutional repository services among respondents. Results also showed 43 (78.2%) respondents use institutional repositories. Nonetheless, interview findings indicate low adoption rate of institutional repositories among students. Visibility and information sharing were factors which mostly influence students to use institutional repositories. Findings further showed library staff and lecturers are sources of awareness and the pulling factors in adoption and use of institutional repositories. The study concludes that information literacy (IL) training is crucial in promoting adoption and usage of institutional repositories. The study recommends academic libraries to establish embedded IL programs to increase adoption and usage. The study also suggests improving the quality of resources in the institutional repositories to reflect students' needs.