The effects of both hydrostatic pressure and electric fields applied perpendicular to the layers on the direct-exciton states in single GaAs – ( Ga , Al ) As quantum wells are studied. Theoretical calculations are performed within the variational procedure, in the framework of the effective-mass and non-degenerate parabolic-band approximations. Both heavy- and light-hole exciton energies and corresponding quantum-confined Bohr radii are obtained. The pressure coefficient is also theoretically evaluated and found in good agreement with available experimental measurements.