A positive gravity anomaly is associated with the Mississippi embayment. When correction for low density sedimentary rocks is made the anomaly is seen to be continuous along the embayment, with an amplitude of 15 to 45 mgals increasing southward. The axis of the embayment anomaly follows the course of the Mississippi river. The seismic refraction profile critical to Ervin and McGinnis' interpretation of a fossil rift cushion underlying the embayment was located on the margin of the embayment anomaly where the structure is most complex. The continuity of the gravity anomaly indicates that a reversed refraction line along this axis, and a reflection line across it, might yield definitive results.