Background.Despite the high burden of pediatric HIV-1 infection in developing countries, there are few data on the clinical course of influenza virus-associated lower respiratory tract infection (LRTI) in these children.Objective.To define and compare the clinical course of HIV-1-infected and -uninfected African children hospitalized with influenza virus associated severe LRTI.Methods.Children with severe LRTI were prospectively recruited between March, 1997, and March, 1999, as part of a broader study evaluating the etiology and outcome of this condition in hospitalized HIV-1-infected and -uninfected children. The results of children in whom influenza A or B virus was identified by immunofluorescent antibody staining after shell vial culture are reported. Viruses isolated were typed by hemagglutination inhibition assays.Results.Twenty-five (21.6%) of the 116 children hospitalized with severe LRTI in whom influenza A or B virus was identified were HIV-1-infected. HIV-1-infected children were older than uninfected children (mean age ± sd 17.4 ± 10.8 monthsvs.10.2 ± 8.9 months;P= 0.002). HIV-1-infected children were more likely to have an underlying medical illness (in addition to HIV-1 infection) predisposing them to more severe LRTI (32.0%vs.13.2%;P= 0.03). HIV-infected children were also more likely to have indirect evidence of bacterial coinfection, including chest radiographic evidence of confluent alveolar consolidation (78.9%vs.35.1%,P= 0.006), and were less likely be wheezing (8.0%vs.31.9%,P= 0.01). However, there was no difference in the clinical outcome of HIV-1-infected and -uninfected children. The duration of hospitalization [median (range) 5 (2 to 33) daysvs.4 (0 to 21) days,P= 0.08] and the mortality rates (8.0%vs.2.2%,P= 0.20) were similar between HIV-1-infected and -uninfected children.Conclusion.HIV-1-infected children hospitalized with severe LRTI associated with influenza virus have an outcome similar to that of HIV-1-uninfected children even in the absence of antiretroviral or anti-influenza virus treatment.