Dissertation (MSc Public Health)Male,s involvement in reproductive health services has been recognized as one of the key strategies in improving reproductive health and accelerating reduction of maternal mortality. Males have a big impact on women,s reproductive health. The determinants of male involvement in reproductive health services have been documented in other parts of the world including Tanzania Mainland but in Zanzibar no published research about male involvement in reproductive health services and male involvement is a key issue on improving reproductive health. This study was conducted in Zanzibar to assess the determinants of male involvement in reproductive health services. Analytical cross-sectional study using interviewer administered structured questionnaire was conducted among 366 randomly selected married males aged 20 years and above. The involvement of males in reproductive health services was measured initially by fourteen key points and then the factor analysis was used to obtain the final level of male involvement index, in which seven key points were used. Analysis was performed using SPSS version 23, chi square test was used to find association between the social demographic characteristics of the respondents and male involvement. Logistic regression analysis was carried out to determine the determinants of male involvement in reproductive health services. Overall, the study found that 41.5% of male had high level of involvement in reproductive health services. In a bivariate analysis the variables that showed a significant association with male involvement in reproductive health services were:-place of residence, age, level of education, source of information, attitude and perceived behavioral control. In a multivariate regression analysis the variables that were found to determine male involvement in reproductive health services were:- source of information from radio (AOR=0.113, 95%, CI 0.062, 0.207), and information from health care provider (AOR= 0.113=95%,Cl 0.058, 0.222), level of education (AOR=0.256, 95% CI 0.074, 0.886) and attitude of male toward their involvement in reproductive health services (Better coefficients = -0.153, CI 0.049, 0.254, P-value=0.004). The study concludes that the level of male involvement in reproductive health services was low because of low male,s attitude. Therefore, there is a need to increasing community awareness and sensitization on male involvement in reproductive health services to change negative attitude regarding male involvement. Innovative strategies on improving male involvement are needed to encourage male involvement in reproductive health services and to change negative behavior regarding male involvement.