A chloride transport vapor phase epitaxial technique has been developed for InGaAsP/InP heterostructures using the "dual-growth-chamber" method. Two independent growth chambers, one for InGaAsP and the other for InP, are connected at an exhausting end. A substrate was transferred mechanically from one chamber to the other within a few seconds without having cross contamination growth at the hetero-interface. Heterostructures with lattice-matched defect-free interfaces of less than 50 Å abruptness have been obtained. InGaAsP/InP DH lasers made by this technique lased in CW at room temperature with thresholds comparable to those made by LPE.