The isostatic transfer function for the southern Mid-Atlantic Ridge was computed from 25 profiles of gravity and topography normal to the ridge trend. As follows from the comparison with previous studies, the transfer function for the Mid-Atlantic Ridge is insensitive to the tectonic setting of profiles used. The experimental transfer function was employed to remove all coherent short-wavelength features in the gravity and topography from 17 long profiles across the southern Mid-Atlantic Ridge. The profiles were then recomputed as a function of t, age of the lithosphere, and averaged over equal ages. The observed regional topography, regional gravity anomaly, and altimeter geoid anomaly agree well with conductive cooling models of the spreading lithosphere. An observed slope of the topography versus t1/2 and of the geoid versus t can be explained with the single set of parameters. Comparison with the estimates by Haxby for the northern Mid-Atlantic and Reykjanes Ridges suggests a systematic decrease in the temperature of the mantle from 1500¿--1600¿C near Iceland to 1000¿--1100¿C at the southern Mid-Atlantic Ridge. The theoretical gravity anomaly deduced by the analytical method of Haxby and Turcotte is sensitive to the thermal parameters only in the age range 0--20 m.y. The fit of the theoretical to the observed gravity anomaly is good outside the axial strip 0--3 m.y. The poor fit at the axis is attributed to inadequacy in the boundary condition of the model.