We present a study on the quality of AlGaInP epitaxial layers regrown on AlGaInP quaternary alloy grooved structure by low-pressure metalorganic vapor-phase epitaxy (MOVPE). The growth behavior and dislocations in the regrown layers are investigated by cross-sectional transmission electron microscopy (TEM). It is found that the dislocation density in the regrown AlGaInP epitaxial layer depends on the growth temperature during the regrowth process. At a low growth temperature, high density of dislocations due to lattice mismatch was observed in the regrown layers. At higher temperatures, regrown AlGaInP layers with drastically reduced dislocation density were obtained.