We have observed changes in the polarization of an evanescent wave pro
pagating in a resonant atomic vapor. The effect can be interpreted as
an effective dichroism and birefringence of the vapor, the phenomenon
characteristic of anisotropic media. In this case it arises from the G
oos-Hanchen shift, which is different for light polarized parallel and
perpendicular to the incident plane. We have also observed Faraday ro
tation of the evanescent wave.