  We study influence of gravitational field on the mass-energy equivalence
relation by incorporating gravitation in the physical situation considered by
Einstein (Ann. Physik, 17, 1905, English translation in ref. [1]) for his first
derivation of mass-energy equivalence. In doing so, we also refine Einstein's
expression (Ann. Physik, 35, 1911, English translation in ref. [3]) for
increase in gravitational mass of the body when it absorbs E amount of
radiation energy.
