LP-MOCVD has been used for the growth of good quality GaAs layers on InP substrates and InP layers on GaAs substrates. The morphology of these layers were excellent and x-ray diffraction measurements show that the InP or GaAs layers are monocrystalline. The near gap luminescence spectrum of an InP layer grown on a GaAs substrate by LP-MOCVD, which is exciton related, is shown. GaInAsP-InP buried ridge structure (BRS) lasers emitting at 1. 3 mu m have been fabricated on GaAs substrates, using the LP-MOCVD growth technique. Pulse threshold current of 190 mA at room temperature has been measured with an output power up to 10 mW.