This monograph aims to explore the possibility of existence of physically meaningful, spherically symmetric exact solutions of general relativistic field equations for a mixture of perfect fluid and radiation. The purpose of searching these solutions is to provide close models for relativistic radiating stars.The first chapter deals with the mathematical formulation of the radiating fluid ball problem with various physical and junction conditions.In second chapter a full discussion is given of Vaidya's (1951)solutions. A number of new solutions have been obtained in remaining three chapters where the line element is conformally flat, an isotropic line element and the most general line element, respectively.This monograph shall be useful to scholars pursuing their research in specialized area of relativistic radiating stars.