A simple method for calculating the ground-state energy of excitons confined in spherical quantum dots is presented. The exciton trial wave function is taken as a product of the ground-state wave functions of the unbound electron and hole in the QD, with a correlation function that depends only on electron-hole separation. A renormalized Schrö dinger equation for the correlation function is deduced by using the variational principle. Both the differential equations for the unbound electron (hole) wave function in the QD and for the correlation function are solved numerically by means of the trigonometric sweep method. The ground state binding energies of an exciton in a GaAs-(Ga, Al)As spherical QD as a function of the dot radius are calculated for the models of square-well, soft-edge-barrier and double-step potentials.Introduction The progress in nanoscale technology has made possible the fabrication of quasi-zero-dimensional quantum dots (QDs), where the excitons remain present even at room temperature because of the quantum confinement increases highly the electron-hole attraction. Although many theoretical studies have been devoted to excitonic states in QDs [1-7], very few papers concerned with effect of the confining potential shape on the exciton energy have been reported. Up to now it has been considered the confinement models with rectangular [1-4], parabolic [5] and charge image [6,7] potentials. The Hamiltonian of an exciton in QD can be separated into center-of-mass and relative-motion terms only in the special case of the parabolic confinement as the electron and the hole effective masses are equal [8]. In other cases, the approximation methods, such as the variational [1-4], matrix diagonalization [5] or finite element [9] have to be used. In this work we propose a simple method that permits to obtain an approximate wave equation for exciton relative motion in a spherical QDs for arbitrary confinement potential by using the variational principle. This equation coincides with the Schrö dinger equation for a hydrogen atom in an effective isotropic space with variable fractal dimension that depends strongly on electron-hole separation. We apply the method to analyze the effect of the confinement on the exciton energy in GaAs-(Ga, Al)As QDs with square-well, soft-edge barrier and double-step confining potentials.