Distributed generation (DG) plays a significant role in reducing real power loss, lowering the operating cost and improving the voltage profile. This paper formulates the DG placement problem a combined objectives as individual objectives and presents a solution method for optimally determining the bus locations and sizing of multiple DG units in distribution networks using biogeography-based optimization (BBO). BBO, inspired from the geographical distribution of biological species, searches for an optimal solution through the migration and mutation operators. Test results on a 33-node distribution network reveal the superiority of the developed method.