Using time-resolved photoluminescence we have investigated the As mole fraction-dependent change from type I to type II band alignments in GaInAsSb/GaSb multiple quantum well structures grown by molecular beam epitaxy (MBE). The decay time becomes longer with increasing As mole fraction of the quantum well region and the time for type II indirect transition is about 1 ns. Relatively high efficiency of indirect radiative transition is explained by the strong enhancement of the overlap of the electron and hole wave functions. (C) 2007 Elsevier B.V. All rights reserved.