Total lymphocyte counts, CD4 T-lymphocyte counts and CD4/CD8 ratios were measured in 30 anti-retroviral-naive HIV-seropositive patients upon hospital admission for acute community-acquired pneumonia (CAP) caused by Streptococcus pneumoniae, and again 1 month after resolution of infection. There was a significant depression of the total lymphocyte count (p < 0.005) and CD4 T-lymphocyte count (p < 0.001) in the acute stage of CAP caused by S. pneumoniae, with a subsequent increase in 90% (27/30) of cases after resolution of the infection. There was no significant difference in the CD4/CD8 T-lymphocyte ratio on admission compared with 1 month later (p 0.9).