Between 1991 and 1995, 2554 children under 5 years old hospitalized with severe acute lower respiratory tract infection in Al-Sabe'en, Sana'a, Yemen were studied. 47.7 per cent (1218) were under 6 months of age and 74.1 per cent (1893) were in their first 12 months. Sixty-four per cent (1633) were males. Of the 2554 cases, 221 died (overall, a case fatality rate of 8.7 per cent). 118 of the deaths (53.4 per cent) were in the under 6 months age group and 188 (85 per cent) were in the first 12 months age group. During 1995 the hospital started adopting the WHO standard case-management guidelines for treating severe acute lower respiratory tract infections. There were no significant reductions in case fatality rates in 1995 (CFR 9.8 per cent) compared with those of 1991 (CFR 7.9 per cent), 1992 (CFR 9.4 per cent), 1993 (CFR 7 per cent), or 1994 (CFR 8.5 per cent). Factors such as late hospital admission with cyanosis, malnutrition, rickets as well as increased resistance of the common causative organisms (pneumococci and H. influenzae) to antibiotics recommended by the WHO may have contributed to such a high case fatality rate remaining unchanged. In addition to reducing the risk of developing pneumonia and dying from pneumonia by improving maternal nutrition, health education, promoting breastfeeding, and preventing rickets and nutritional anaemia among the vulnerable age groups, vaccination against pneumococci and H. influenzae type b should be seriously considered as one of the strategies to reduce lower respiratory tract infection-related mortality.