Roost use by African bats is poorly known, particularly for those using cavities in trees. Two sympatric species of Scotophilus were fitted with transmitters and tracked to their respective roosts in a natural savanna site in Swaziland. Both species roosted exclusively in trees, apparently preferring Combretum imberbe trees with large girths. The conservation of such roosting trees may be critical to the continued persistence of cavity-nesting insectivorous bats in African savannas.