Compliance with HIV treatment has been studied extensively. Following the introduction of tritherapy, its importance and implications have changed. Antiretroviral treatments entail taking up to 20 pills a day at set hours, for which there are often numerous undesirable and even toxic side effects. These therapeutic constraints lead to what is labeled greater or lesser compliance, Certain factors such as side effects, modes of contamination, and trust in physicians appear to be more closely linked to noncompliance than others. A recurring problem is how to assess this compliance. There are two types of measures that serve this purpose: direct (biological) or indirect (interviews, questionnaires). It is often very difficult to know how authors actually proceed in assessing their patients' compliance. To determine this, we analyzed 27 of the 310 studies published between 1990 and 2000 on therapeutic compliance in HIV-infected patients. These 27 studies were not chosen because they are a statistically representative sample of the related literature, but because they account quite well for the different types of methods used to measure compliance with HIV treatment. Our analysis shows that compliance measures are quite diverse and can be either a combination of direct and indirect measures, or consist of one or more direct measures or only indirect measures. These three methodological orientations are discussed first, The limits and biases of self- and hetero-compliance assessment, so often neglected, are studied next. Finally, problems related to the temporal facet of compliance behavior are analyzed, namely definition of the concept, need for a more precise theoretical elaboration, and the place of health psychology in relation to the medical sciences.