Of a total of 908 pediatric AIDS cases, 78 percent have acquired HIV infection from a mother with HIV infection or at high risk for acquisition of HIV, and the number of cases in children is expected to increase over the next several years. AZT therapy may be effective in altering the course of the disease and decreasing the high mortality in these children. It is also possible that early intervention with AZT may prevent the establishment of HIV contracted before, during, or just after birth.