The presence of antibodies against the HIV protein of 24 kd was studies by the parallel use of the DAVIH BLOT western blot and of the DAVIH AC P24 ELISA in serum samples from 176 patients at different HIV-1 infection stages. The results were correlated with the clinical classification of the patient at the moment of taking the sample and with the further evolution during 6 months. 57% of the patients with opportunistic minor infections and 96% of AIDS patients had low antibodies titres. Dead patients showed no reactivity or presented very low titres in samples taken before dying. Different titrations were observed in serum groups with an apparently uniform reactivity in the western blot. The results show and adequate clinical and serological correlation. Therefore, the DAVIH AC P24 ELISA could be useful in the clinical follow-up of HIV-1 infected persons.