The first simultaneous Na lidar and Medium Frequency (2.66 MHz) Doppler radar observations of vertical winds in the mesosphere (79.5--100 km) above Urbana, Illinois are reported. The lidar and radar systems were operated simultaneously for a 24-h period during January, 1989. The lidar measured Na density profiles and the radar measured the vertical component of velocity. The Na density data was used to derive the vertical velocity using the continuity equation. This data set provides a unique opportunity to check the consistency of parameters measured by the two very different experimental techniques. Excellent agreement is found between the radar velocities and the velocities inferred from the Na density on the bottomside of the Na layer. Significant differences are found between the velocities obtained with the two techniques on the top side of the Na layer. Possible reasons for this discrepancy are discussed. ¿ American Geophysical Union 1990