Background information: today, HIV infection is a serious public health problem. However,rnthe advent of highly active antiretroviral treatment (HAART) has dramatically improved thernprognosis for HIV-positive patients, substantially reducing the rate of disease progression andrndeath; but HAART Adherence is found to be critically important for the success of therntherapy.rnObjectives: the objective of this study was to determine the degree of antiretroviral treatmentrnadherence and its associated factors in all people living with HIV/AIDS on highly activernantiretroviral therapy (HAART) and follow up at ART - units of Adamma and Jimmarnspecialized hospitals in Oromiya regional state from July to August 2006.rnMethods: a cross sectional survey design, using both quantitative and qualitative methods,rnwas used to conduct the study. A total of 459 people living with HIV/AIDS treated withrnhighly active antiretroviral drugs invited to complete sets of variables using an interview andrnself-administered methods to elicit information on variables of demographic characteristics,rnARV drugs, psychological & socio-environmental factors, and substance abuse, emotionalrndistress, perceived social support, ART services & care providers respectively.rnOf the total respondents, 265 [57.7%] and 194 [42.3%] were females and males respectivelyrnwho participated in this study. A total of 300 [65.4%] respondents were in the age range ofrn26-35 years while, 94 [20.5%] were in the range of 18-25 years.rnAdherence to antiretroviral therapy in the previous three days of the interview was measuredrnby self-report. Initially, the percent of adherence was calculated for each drug by dividing thernnumber of pills taken by the number of pills prescribed. Then, the percent of adherence to thernantiretroviral regimen was estimated by the average of adherence to the drugs.rnPatients who reported an intake of 95% of the prescribed medication were considered to bernadherent. Data was checked for multi-co-linearity and comparison of PLWHA who werernadherent and non â€“ adherent (taken < 95% of their doses of antiretroviral medications) groupsrnwas determined on important variables. The significance level was measured using 95% CIsrnof adjusted and crude odds ratios for which, P 0.05 were considered significant.rnFurther, the independent predictors of adherence were also assessed using a sequence of twornmultivariate logistic regression models; so that the variables that had significant effect onrnadherence (p