The sequence of seasonal events that occurs each Martian year around the two poles of Mars is more precisely described due to the input of new telescopic surveys and polarimetric measurements, combined with available orbital photographs, Viking lander images, and atmospheric pressure recordings. The interplays between vaporization and condensation of both carbon dioxide and water products, seasonally at work around both poles, produce clouds and mists in the atmosphere and frosts and ices at the surface. The succession of occurrences of prepolar hood frost depositions, polar hood formations and evolutions, and surface cap depositions and vaporizations is described for both poles as a function of the seasonal evolution parameter Ls (planetocentric longitude of the Sun). ¿ American Geophysical Union 1996