Recent calculations of the Martian obliquity suggest that it varies chaotically on timescales longer than about 107 years and varies between about 0 and 60¿. We examine the seasonal water behavior at obliquities between 40 and 60¿. Up to several tens of centimeters of water may sublime from the polar caps each year, and possibly move to the equator, where it is more stable. CO2 frost and CO2-H2O clathrate hydrate are stable in the polar deposits below a few tens of meters depth, so that the polar cap could contain a significant CO2 reservoir. If CO2 is present, it could be left over from the early history of Mars; also, it could be released into the atmosphere during periods of high obliquity, causing occasional periods of more-clement climate. ¿ American Geophysical Union 1995