Correct procedures for the reduction of marine gravity data for the purpose of geophysical modeling, as established by previous authors (e.g., Bomford, 1962), include addition of a correction term necessitated by the undulation of the geoid surface on which gravity is measured. The variation of gravity that is due to the undulation of the geoid is known as the indirect effect. Although this correction is generally small and has not been commonly applied in marine geophysical modeling, there are cases in which it becomes significant. For regional studies in which the long-wavelength components of gravity (λ > 500 km) are analyzed, adjustments must be made to remove the indirect effect and avoid the possibility of serious misinterpretation. For local studies in which shorter-wavelength components are considered, gravity values may be satisfactorily approximated while neglecting this small correction.