We show that a strong case can be made for an intrinsic magnetic field of dynamo origin for Mars earlier in its history. The typical equatorial magnetic field intensity would have been ~0.01--0.1 Gauss. The earlier dynamo activity is no longer extant, but a significant remanent magnetic field may exist. A highly non-dipole magnetic field could result from the remanent magnetization of the surface. Remanent magnetization may thus play an important role in the Mars solar wind interactions in contrast to Venus with its surface temperatures above the Curie point. The anomalous characteristics of Mars' solar wind interaction compared to that of Venus may be explicable on this basis. ¿ American Geophysical Union 1988