In this letter, a compact cross-shaped slot antenna with a coplanar waveguide fed rotated patch is presented and experimentally studied. By properly designing the dimensions of cross-shaped slot and rotated patch, good UWB property can be obtained. In comparison with the previous slot antennas, the proposed antenna has a smaller size as high as 35 mm×33.8 mm . The measured impedance bandwidths, for reflection coefficients less than -10 dB, range from 2.55 to 12.01 GHz, which can cover UWB frequency ranges (3.1–10.6 GHz). Moreover, the novel antenna has nearly omni-directional radiation patterns, steady radiation efficiency and good gains in the UWB ranges. These results prove that the antenna exhibits good characteristics and is suitable for portable mobile ultrawideband (UWB) applications.