MOCVD grown quantum cascade lasers (QCLs) have demonstrated about the same level performance as MBE grown QCLs. With the regrowth capability to fabricate buried heterostructure (BH) waveguides, the QCL output power has been dramatically increased and that opens the door to many mid-IR (and THz) applications. With the stable and high growth rate to produce high performance and reliable BH lasers, commercialization of QCLs with reasonable qualification and affordable price becomes possible. Furthermore with a good gain material and the etching and regrowth capability, optoelectronic integration can be realized using MOCVD growth techniques. We compare the MBE and MOCVD growth techniques and discuss important issues on growth rate stabilization and the control of growth quality at the hetero-interface. We also go over a few growth and integration examples we are working on, which are preferentially done by MOCVD. Finally we describe a detailed QCL BH regrowth study and discussed how to obtain optimized current-blocking regrowths.