The use of systems to detect the presence of 24kd protein as well as the levels of antibodies to it, is very useful in the follow-up of HIV-1 infected individuals. To develop these systems it is necessary to have this protein purified. The present paper describes the purification of p24 starting from the semipurified viral flattening on saocaharose gradient, using immunoaffinity chromatography with monoclonal antibodies coupled to Sepharosa 4B activated with cyanogen bromide. For the characterization of the purified product it was used polyacrylamide gel electrophoresis with silver staining and immunoelectrotransference. As a result, it was obtained p24 which can be used for the development of diagnostic tools and monoclonal antibodies.