This study of the relationship between mortality risks of siblings born to the same mother shows that, in Bangladesh, the death of the immediately preceding sibling in its infancy has a negative influence on the survival chance of the child in question in its infancy; however, death of the preceding sibling appears to have a positive influence on the index child's survival at ages 1-5 years. Similar results are found for the survival status of the two preceding siblings. Preceding birth interval length and survival status and sex of the immediately preceding sibling are also significant predictors of child mortality between ages 1 and 5 years. Possible explanations may be that the index child faces stronger competition from its immediately preceding brother than from its immediately preceding sister, or that the index child is likely to be looked after more by its preceding sister than by its preceding brother.