This study proposes a procedure to estimate the number of orphans due to maternal AIDS. The procedure estimates the number of orphans by calendar year, multiplying the cumulative fertility rate by the number of AIDS deaths among women aged 15-49 years. Because the procedure refers to the number of children that are alive, the estimate is adjusted by contemplating the proportion of pediatric AIDS cases due to vertical transmission and the probability of survival in the 5-9-year age group. To estimate the number of AIDS orphans in Brazil from 1987 to 1999, the procedure was applied by stratifying according to geographical region, taking into account the differences in regional fertility rates, completeness of death reporting, and misclassification of AIDS-related deaths as due to other causes. The total number of cumulative AIDS orphans for 1987-99 was estimated at approximately 30,000.