284 sera from blood donors in Rio de Janeiro, were submitted to the Subin-Feldman reaction (RSF) and to the indirect fluorescence antibody (RIAF) reaction for toxoplasmosis. In both reactions, 37 negative results were observed. 216 positive results and 31 results were positive by one test and negative by the other. Among these last results, there were more positive results by RSF than bu RIAF. The percentage of agreement of the positive or negative results in both reactions was 89%. Among 216 sera that reacted by both tests. 143 showed indical titres that represented a proportion of 66.2%. Positive titres that were different by only one quadruple dilution being taken into consideration, the proportion of agreement among these positive results increased to approximately 99%. The present results confirm the close parallelism between the two reactions; the RIAF can be used as a routine for the sorological diagnosis of toxoplasmosis.