The effects of structure parameters and hydrostatic pressure oil the electronic states and the second harmonic generation (SHG) susceptibility of asymmetric rectangular quantum Well (ARQW) are studied. The asymmetry of the potential can be controlled by changing the structural parameters and this adjustable asymmetry is important for optimizing the SHG susceptibility. We have calculated analytically the electronic states in ARQW within the framework of the envelope function approach. Numerical results for Al-x/Ga1-x/As/GaAs/AlxrGa1-xr. As quantum well are presented. The results obtained show that the hydrostatic pressure and the structure parameters of ARQW significantly influence the SHG susceptibility. This behavior in the SHG susceptibility gives a new degree of freedom in regions of interest for device applications. (c) 2007 Elsevier B.V. All rights reserved.