This article refers to the research discussion based on methodology of content analysis, which aims at making explicit the horizon of rationality of the services provided for alcohol users and other drugs in the Great Florianópolis region, to contribute to the establishment of qualitative parameters in the evaluation of health services. It was verified that there is a hegemonic conception about the drugs dependence phenomenon as well as the way to intervene in this phenomenon, synthesis of different and, sometimes, contradictory rationalities. The model of this conception is based on the notion of disease, on the pursue for abstinence, on the struggle to control de addiction, operating medical-therapeutic and moral apparatus. On the basis of this conception, there is a subjectivist, moralist and psychopathologizing perspective, constituting a historical and not very critical view of the social production around the use of drugs, grounded on a rationality of metaphysical predominance, even when blended with other rationalities such as the scientific. In this article we will discuss the importance of correlating the "horizon of rationality" in the health services with the problematic of effectiveness and efficiency of treatments on the area of drugs dependency.