We investigate the flow patterns in a cylindrical rotating Rayleigh-Benard convection cell with radius-to-height ratio Gamma = 0.5. The Rayleigh number R is 2 x 10(8), the dimensionless rotation rate Omega varies from 9.6 x 10(3) to 4.8 x 10(4), and the convective Rossby number Ro is between 0.31 and 0.06. Measurements of the velocity field in the volume adjacent to the top of the cell are acquired with a scanning particle image velocimetry (PN) system. We present quantitative results for velocity and vorticity of the cyclonic and anticyclonic vortices characterizing the convection, as well as for the dependence of the vortex size on the rotation rate and variation of vorticity with depth. Copyright (C) 1998 Published by Elsevier Science B.V.