The purpose of this study was to investigate the usage patterns of OAIRs among university community members in Tanzania universities. The Unified Theory of Acceptance and Use of Technology (UTAUT) model used to guide this study. The study employed a cross-sectional research design. Systematic random and purposive sampling procedures were used to obtain a total of 292 respondents and eight key informants respectively. Questionnaires and interviews were used to collect quantitative and qualitative data. Quantitative data were analyzed by using SPSS and qualitative data were analyzed by using content analysis. The study found that 54.5% of the respondents indicated the use of OAIRs are to collect, preserve and disseminate scholarly publications and 54.5% to provide information resources for teaching, learning, and research. The study found that faculty members are using OAIRs very often. 66.4% of the respondents indicated that factors motivate to use OAIRs are to enjoy access to articles without hindrance and charges, 54.5% provisional of open access to a wider audience of researchers and 47.4% to increase the impact of researchers’ work. The study found that challenges influencing the use of OAIRs are low level of awareness, lack of ICTs infrastructure and lack of skills in using OAIRs. The study concludes that there is still much to be done in Tanzanian universities to improve the extent of OAIRs usage. The study recommends for provisional of skills in using OAIRs, stable ICTs facilities such as enough computers, Internet, and creation of more awareness on the use of OAIRs
