Analysis of quantitative information on photochemical migration of hydrogen atom, proton, acylic and arylic groups in anthraquinone derivatives obtained by experimental and quantum-chemical methods has been performed. The migration of acyl is found to occur in the ππ* state and to be thermally reversible. The concepts of conservation of orbital symmetry in the photochemical process are applied to account for the relation of the compound reactivity investigated to the chemical structure. Data from quantum-chemical calculations and experimental spectroscopy are used to construct energy correlation diagrams. The 3nπ* state is found to be reactive in hydrogen photochemical migration. Aryl migration proceeds non-adiabatically without conserving the excitation. The dependence of rate constants of thermal migration of hydrogen atom and acylic group on substituent nature, medium and temperature is studied. A quantitative theoretical interpretation of the results based on calculations by the PPP method is proposed.