The wind speeds and the significant wave heights derived from the Geosat altimeter are validated by comparing with the data obtained at Japanese ocean data buoy stations. A systematic error is found in the altimeter wind speeds at high winds. An experimental equation is derived in order to correct this error for the present study. By using the corrected wind speeds and the wave heights, growth of wind waves with fetch in the Japan Sea under winter monsoon is investigated. The altimeter-derived nondimensional significant wave height and nondimensional fetch show good agreement with the empirical fetch graph formulas. Fetch variation of the wind speeds is also discussed in relation to the evolution of the turbulent boundary layer over wind waves by using the altimeter data. ¿American Geophysical Union 1992