Measurements of the turbulence intensity over and beyond a smooth disk rotating in a quiescent air are presented in this study. The apparatus consists simply of a disk rotating horizontally about its vertical axis. A hot wire anemometer, with a single sensing wire, joined to the fully transistorized DISA 55M electronic circuit is employed in the measurements of the mean velocity as well as the turbulence intensity. A stroboscope is employed to measure the disk rotational speed and an oscilloscope is used to detect the transition region over the disk surface. The results are presented to show the profiles of the turbulence intensity in the axial direction over the whole range of the boundary layer (at various radii), starting from the disk surface (or the disk-center plane) and ending at the edge of the boundary layer. Variations of the turbulence intensity with the radial direction (at constant values of the axial distance) are also investigated. In addition,the investigation is extended to include the effect of the disk rotational speed.