The Rubino reaction was studied in 178 leprosy patients to correlate its positivity, clinical form, E.N.L., and time and activity of the disease. The patients studied were classified according to the criteria established by the 1953 Madrid Congress. The results show that the tuberculoid patients presented negative Rubino reactions regardless of any of the parameters studied. The borderline patients showed 9% positive Rubino reaction not related to any of the observed parameters studied. The lepromatous patients showed a significant difference of positivity to the Rubino reaction when grouped as to the disease's active or non-active presence. Active lepromatous patients showed 55% of positivity to the Rubino reaction whereas patients considered clinically inactive showed only 6% of positivity. The fact that the Rubino reaction is negative in the majority of patients who are clinically cured would indicate that this test could be included as part of the criteria used in determining which clinically cured lepromatous patients can discontinue medication without risking a relapse.