The first observations of mesospheric winds made between January-August 1990 with an MF partial reflection radar located on Christmas Island (2 ¿N, 157 ¿W) in the central Pacific are described. The mean zonal winds are in general westward, but show clear evidence for a wave-driven circulation. Power spectral studies indicate that waves are present over a wide range of periods. Ultrafast Kelvin waves are especially evident in January--March, with peak amplitudes ~20 m s-1, and intrinsic phase speeds of ~150 m s-1 indicated. The Kelvin waves are estimated to contribute an eastward acceleration of up to 10 m s-1 day-1. Gravity wave amplitudes are also found to be almost as large as those observed at mid-latitude sites, which suggests that convection is a major source of gravity wave activity. ¿ American Geophysical Union 1991