Eleven HIV-infected and 30 otherwise healthy children hospitalized for H1N1 influenza were studied. Leukopenia was recorded in 64% of HIV-infected and in 20% of healthy children (P = 0.01). Chest radiograph was abnormal in 18 (46%) children. Interstitial pneumonia was more frequent in HIV-positive children and consolidation was more frequent in HIV-negative children. Although the duration of symptoms and hospital stay was significantly longer in HIV-negative than in HIV-positive children, only 37% of HIV-negative children and 91% of HIV-positive received oseltamivir. The H1N1 influenza attack rate was very high (20%) in HIV-infected children, but it consistently ran a mild course.