A B S T R A C TBackground: An exhaustive review of the main worldwide psychiatry-related literature sources shows that the present antidepressants' classification does not have a logical and epistemic nomenclature oriented to allow a quick recognition of main adverse drug reactions (ADRs) and pharmacodynamic interactions. Methods: The study was performed in two phases. In the first, a new classification of antidepressants was built up based on their mechanisms of action. Furthermore, relevant ADRs and pharmacodynamic interactions were grouped according to their causal mechanisms.In the second phase a comparative, prospective, longitudinal, experimental and randomized study was performed.312 physicians who were great prescribers of antidepressants were randomly assigned to one of two groups, A and B, having 156 physicians each. Each group was assessed with a questionnaire evaluating basic knowledge of the most important ADRs and pharmacodynamic interactions. This questionnaire was provided before and after the assignment of a standard classification (group A) or the new classification (group B). In the questionnaire provided after the assignments, some questions about different acceptance variables were included. Results: After handing the classifications, significant differences were found (p = 0.0008) in the number of correct answers in the second questionnaire, in favor of group B. In addition, analysis of acceptance variables showed significant differences between both groups, in favor of the new classification. Conclusion: This study shows that the new classification of antidepressants allows, in contrast with the standard classifications, to quickly inform and enable physicians to easily relate each drug to important ADRs and pharmacodynamic interactions.