Introduction : Western Blot (WB) is the most commonly used method to confirm the presence of antibodies against Human Immunodeficiency Virus type 1 (HIV-1). The interpretation of WB, however, poses difficulties since of the multiplicity of criteria proposed by various international organizations. Some criteria generate an unacceptable number of indeterminate results, thus preventing the early management of patients. The present work aims to evaluate the different criteria for interpretation of WB according to various organizations compared to viral load test.Material and methods : This is a study carried out on a total of 2 618 Western Blot profiles registered during a period of 56 month (from January 2013 to September 2017) at the Laboratory of Medical Analysis of Regional Hospital Center in Agadir.Results : The results obtained indicate that some organizations have very interesting values concerning the positivity of the WB profiles; WHO (94.84%), CDC/ ASTPHLD (94.61%) and SFTS (93.09%). For the negative profiles, all the organizations have identical values with 3.59%. Regarding indeterminate profiles, the WHO gave the minimum of these cases (1.57%) followed by CDC / ASTPHLD (1.8%) and SFTS (3.32%). The WHO provided very interesting values for sensitivity (98.93%), specificity (91.26%), positive predictive value (99.64%) and negative predictive value (74.60%). Similarly, the CDC / ASTPHLD criteria remain favorable and are highly consistent with those of WHO (p = 0.8113).Conclusion : Sensitivity, specificity, and predictive values are characteristics of WB test that interpret the results and allow applying them to patients. In our context, it is recommended to adopt the WHO criteria to facilitate the interpretation of western blot profiles. The CDC / ASTPHLD criteria remain favorable to adoption.