Twenty-two pediatric patients with AIDS required assisted ventilation during 27 pediatric ICU (PICU) admissions. Patients were retrospectively divided on the basis of whether they required assisted ventilation for acute respiratory failure (ARF) or for another reason. Sixteen (59%) courses of assisted ventilation were for ARF. The PICU mortality rate was 81% for the ARF group. Eleven (41%) courses of assisted ventilation were for reasons not involving ARF. The PICU mortality rate for the group without ARF was 9%, significantly lower (p less than .01) than for the ARF group. Pneumocystis carinii pneumonia (PCP) was documented during 48% of admissions. Occurrence of PCP did not affect mortality, nor was it more likely in those with than without ARF. Two patients with ARF survived to discharge from the hospital. Both died within 1 yr of ARF. Thus, the short-term prognosis for pediatric AIDS patients requiring assisted ventilation for ARF is extremely poor.