Despite the increase number of people living with HIV still there are limited information about the factors associated with viral load suppression among HIV+ individual enrolled into HIV care and treatment centers in Tanzania. Data reports that 87% of those who are living with HIV have attained viral suppression. However this is still low compare to the UNAIDS global targets that by 2020 of 90% on treatment must achieve viral suppression. Viral load remains a gold standard for assessing treatment outcome for those who are on treatment. In 2014 UNAIDS introduced 90- 90-90 goal so as to combat HIV epidemic by 2020. First 90% know there status, second 90 accessing treatment and Third 90% viral suppression. The aim of this study was therefore to identify factors affecting viral load suppression among HIV+ adults attending care and treatment services in the regions. Crossectional analytical study conducted at Dodoma, Mtwara and Lindi regions in randomly selected health facilities. 459 participants who are on ART for atleast 12 months and 18+ years were recruited for the study. Structured questionnaire was used. Data was entered, cleaned and analyzed using EPI info 7.2.2.16. Odds ratio was used to establish association, 95% CI, and P value of 0.05 were used for statistically significance. A total of 459 study participants were enrolled.