A model has been developed for CW operation of InGaAsP Double-heterostructure (DH) lasers considering Auger recombination as the major source of nonradiative recombination inside the active region. The model uses a two dimensional temperature distribution solution inside of the active layer of stripe geometry InGaAsP DH lasers to get better average value for the active region temperature. Then, utilizing Haug's model of threshold current density for lasing, together with Asada and Suematsu's model for the external differential quantum efficiency, the light output power P[subscript]L as a function of the injection current I is obtained;The developed model allows us to make a theoretical study of P[subscript]L versus I characteristics of a laser under CW (continuous wave) operation. The effect of changes in the heat sink temperature T[subscript]H, in the doping concentration level of the active layer, and in the dimensions of the passive layer as well as the active layer upon the optical output power are investigated in detail. It is shown that quantities like P[subscript]Lm (the maximum value of P[subscript]L), I[subscript]m (the value of injection current at which P[subscript]L takes its maximum value), [delta] I (the range of injection current over which CW operation is possible), and [delta] T[subscript]H (the range of heat sink temperature over which CW operation is possible) vary significantly with the heat sink temperature T[subscript]H, the doping level of the active layer (p[subscript]0 for the p-type and n[subscript]0 for the n-type doping), and the dimensions of the active and passive layers. For instance, P[subscript]Lm and [delta] I decrease as T[subscript]H increases, while P[subscript]Lm, [delta] I, [delta] T[subscript]H, and I[subscript]m tend to increase for some doping levels. Thus, the results suggest that proper doping of active layer of laser is desirable;The result of our theoretical study shows that there is a strong evidence that Auger process plays a major role in influencing the P[subscript]L versuv I characteristics of an InGaAsP DH Laser under CW operation because this process could contribute significantly to the internal heating of the device, thereby leading to acute temperature sensitivity of the laser output;The model developed in the present study should also provide an intuitive and rapid way of finding such laser parameters as the threshold current I[subscript]th for lasing and the quantum efficiency [eta][subscript]d for pulsed as well as CW operation of an InGaAsP DH laser. This should be useful to future designers of semiconductor DH lasers.