A band-notched ultra-wideband (UWB) printed antenna is introduced. The radiation element is a rectangular patch fed by a coplanar waveguide (CPW), both etched on the same side of a substrate. The bandnotch characteristic is realized by cutting two L-shaped slots in the radiation element. A detailed parametric study of the slots is presented. Simulation results show that the slot length determines the center frequency of the notch band, and the width, shape and position of the slots affect the notch bandwidth. The antenna impedance bandwidth covers the 3.1～10.6 GHz frequency range and effectively eliminates the 5.15～5.35 GHz WLAN range. The proposed antenna is suitable for applications in cellular systems and UWB systems.