摘要Objective:The study was carried out in order to determine the following objectives:(1)To determine the pro-portion of patients who state achieving or not achieving optimal adherence to antiretroviral therapy (ART)in selected Care and Treatment Sites in Arusha and Dares Salaam regions in Tanzania.(2)To identify factors such as structural,cultural or disease related contributing to sub-optimal adherence to antiretroviral (ARVs). (3)To assess quality of operating structures and processes for provision of antiretroviral (ARVs)in the select-ed healthcare facilities.(4)To document suggestions and proposals for improving ART adherence among ARV users.Methods:Data from 7 studied facilities (3 public and 4 private /or faith based)includes 207 interviews from ARV users,28 staff interview staff,26 observations during consultations,8 focus group discussions,10 key informant interviews,and stock checks in 6 facilities.The study design was a cross-sectional using both qualitative and quantitative data collection techniques.Quantitative data were collected by using an adherence tool check list,while qualitative data were obtained using a consultation observation checklist,semi-structured interviews,focus group discussions (FGDs)and key informant interviews.Results:There were slight varia-tions in the quality of operating structures and processes in the two studied regions.However results indicate that ARV adherence in Arusha region was comparatively similar to that of Dares Salaam.The composite adher-ence for one month in seven facilities was 90 % and only 21 % of ARV users achieved optimal adherence. Conclusion:The overall mean composite adherence rate of 90 % in the two areas surveyed is encouraging. More efforts to improve the quality and processes of operating structures in our study facilities and others in Tanzania are needed to ensure optimal adherence among the larger group (79 %)of ARV users who are cur-rently taking less than the critical 95 % of their medications.