Mother to child transmission (MTCT) occurs when an HIV positive pregnant mother passes the virus to her unborn baby, during delivery or sometime after delivery. It is estimated that without prophylaxis treatment 15-30% of babies born by HIV positive mothers will acquire HIV infection during pregnancy and delivery, while 15-20% will be infected during breast feeding. Since the HIV prevalence among pregnant women (at ante natal Clinics) in Tanzania is 8%, this pinpoints the strong need of effective HIV infection prevention of mother to child transmission program (PMTCT). The factors affecting PMTCT services are home delivery, social support and engagement of male partner. Male participation is expected to increase the aspiration of the pregnant mother in the comprehensive PMTCT interventions and adherence to prophylaxis treatment. Objective The main objective of this research was to determine the prevalence and factors associated with male involvement in prevention of mother to child HIV transmissionservices in IringaMunicipality. Methodology Study design is descriptive cross sectional using qualitative and quantitative. In the quantitative part of the study, the participants were married men of age 23 years and above. Data were collected through questionnaire andanalyzed using SPSS version 16. For each categorical variable we calculated proportions together with 95% confidence intervals.Unadjusted and adjusted analyses of factors associated with male involvement in PMTCT were calculated by logistic regression models obtaining odds ratios, 95%CI and P-value of the association. For the qualitative part,7 Male Village Executive Officers (VEOs) were interviewedfrom Kihesa ward in Iringa Municipality. The interview guide with probing questions was used to collect data and the analysis was done using thematic approach.Permission to conduct the study was obtained from KCMUC research ethical committee and Municipal Executive Director (MED) of Iringa. Privacy and confidentiality wereassured. Results A total number of 420 men were recruited in the study. The results show that male involvement in PMTCT is very high in Iringa Municipality. Nearly two third males had ever gone to PMTCT clinics with their wives (74.0%, 95%C.I. = 69.7 – 78.2). When asked about their willingness to go with their wives to PMTCT clinic, 79.2% (95%C.I. = 75.3 – 83.2) showed willingness to escort their wives to PMTCT clinics.However demographic characteristics were found to be the main determinant in male involvement in PMTCT. Malesof young age 30-39 are significantly associate to support their wives than those of old age in adjusted odds ratio.Participants also showed awareness on PMTCT services and the specification of the PMTCT package while others have HIV knowledge but lack PMTCT awareness. Conclusion The prevalence of male involvement in PMTCT services was high by 74%in Iringa municipalityand large numbers of males are aware of this program. Theyparticipate although an economical factor has been mentioned ashindrance of their full participation. The study found that, lack of money; poor education; setup of PMTCT service package; culture and tradition, unfriendly environment for service provision and distance from the health facility to residence are the barriers to male involvement in PMTCT. The general findings show that, the PMTCT services should be supported by community sensitization for effective prevention of mother to child transmission, specifically targeting mothers and their partners. This can lead to full participation of men in the PMTCT program. Also the setup of the PMTCT programme should consider both genders.