The influence of HIV I p24 antigen immune complexing with anti-p24 antibodies of the assessment of their respective levels in HIV-positive sera was studied. ELISA tests were used for evaluating anti-p24 and p24 antigenemia, with or without acid dissociation. We have observed that: 1. p24 antigenemia usually coexisted with low anti-p24 levels, an inverse correlation between these two parameters being traced; acid dissociation increased the percentage of p24 positive sera, especially when anti-p24 titers are low; 2. on contrary, after acid dissociation, p24 Ag remain undetectable in 55.56% of patients presenting high titers and 29.41% of those with low levels of anti-p24; acid dissociation do not increase anti-p24 titers. Whereas the first group of observations suggests that p24 Ag and anti-p24 Ab may be involved in immune complexes, the second set indicates that p24 Ag and Ab were not inevitably linked in such complexes. So, they may be indicative for two distinct biological phenomena.