Crustal magnetic field anomalies are calculated at several altitudes above the Tharsis region on Mars assuming a source region consisting of uniformly magnetized subsurface volcanic constructs. The subsurface structure is consistent with a proposed model for the evolution of the Tharsis province based on geologic and tectonic evidence. The maximum thicknesses of subsurface volcanic deposits are constrained by gravity and topography data. Mean magnetization intensities are assumed to be comparable to those of SNC meteorites. Because reversals of the former Martian dynamo are neglected, the calculated field magnitudes may represent an upper limit on actual fields to be expected above the Tharsis region. Maximum field magnitudes at 300 km altitude are in the range 1--5 nT and would be marginally detectable by an orbiting magnetometer.¿ 1997 American Geophysical Union