There are limited published investigations about adherence to antiretroviral and its determinants. Many determinants influence on adherence to therapy. The effects of some determinants on adherence are controversial. More studies are needed to be fulfilled about adherence and its determinants to compile strategies. Key to the success of antiretroviral therapies is the ability and willingness of HIV-positive individuals to adhere to antiretroviral regimens. There are different definitions for full adherence. In the most studies, adherence is defined as taking =95% of prescribed medication. Adherence rate needs to be >95% to prevent virologic failure and for complete supper-ssion. The consequences of poor adherence include not only diminished benefits for the patient, but also the public health threat of the emergence of multidrug-resistant viruses, as these resistant strains can then be transmitted from a patient to their contacts. Evaluating adherence has proven to be difficult and there is no gold standard for evaluating adherence to medication. Adherence is assessed in various ways. The most studies evaluate adherence to treatment by using patient's self report and the pill count method but these are methods known to overestimate adherence. Some determinants are associated with adherence include: age, gender, addiction specially injection drug users, alcohol consumption, depression, social support, level of education, work situation, adverse antiretroviral effects, pregnancy, type of antiretroviral drug regimen, number of pills and daily doses received, severe traumas, social and psychological factors, and relationship between clinician and patient.0