Sabin-Feldman reaction is being analyzed in what regards diagnosis and control of cure of toxoplasmosis, an evaluation based fundamentally upon experience, including observation of the evolutive character of the acquired, lymphoglondular form of the infection. These considerations, dealing with the different aspects at issue are exposed as follows: - introduction; - grades of positivity of the Sabin-Feldman reaction; - relation between the grades of positivity of Sabin-Feldman reaction and the seriousness of toxoplasmosis; - specificity of Sabin-Feldman reaction; - sensivity of Sabin-Feldman reaction; - differentiation between toxoplasmosis-infection and toxoplasmosis-disease by means of Sabin-Feldman reaction; - the raise of Sabin-Feldman reaction and the period of time required for confirmation of the diagnosis of toxoplasmosis-disease; - Sabin-Feldman reaction and the control of cure of toxoplasmosis; - oscillation in the results of Sabin-Feldman reaction; - comparison of results yrovided by Sabin-Feldman reaction and by immunofluorescence for the diagnosis of toxoplasmosis; - advantage of a concomitant performance of Sabin-Feldman reaction and the complement fixation test; - further observations regarding Sabin-Feldman reaction; - the importance of a careful interpretation of Sabin-Feldman reaction.