The effect, hitherto neglected, of core loss of nonlinear inductors has been considered in the analysis of a parallel ferroresonant circuit. Some generalised conclusions based on mathematical proofs are made to give deeper physical insight into the effects of core loss on: (a) the critical values of linear system parameters for the onset of ferroresonance; (b) jump-from points; (c) percentage unstable zone; (d) susceptibility to ferroresonance; and (e) jump-to points and jump severity. A comparative study of the theoretically computed response curves with and without loss and the one observed experimentally for a parallel ferroresonant circuit shows that agreement between the experimental observations and the computed results is closer when core loss is included. Further, the experimentally observed critical values of resistance and inductance are closer to the theoretical values obtained when core loss is included.