Data from the Solar Mesosphere Explorer satellite of polar mesospheric clouds have been used in determining the variation of cloud height from 1981 to 1985. Applying various corrections to the apparent tangent heights measured at the atmospheric limb, we find no significant variation of height within an individual cloud season (-10 days to +50 days relative to summer solstice) either with latitude or local time. Furthermore, no significant year-to-year variation is found over the 4-year time span. We find significantly higher (2 km) PMC cloud heights in the north than in the south. The average value of 85.0¿1.5 km for the northern PMC is in good agreement with measurements from the OGO-6 satellite, rocket-borne photometers and ground-based triangulation of noctilucent clouds.