A novel compact internal hepta-band planar monopole antenna for mobile devices is presented. The antenna element occupy 35.5 mm × 15.5 mm and is installed on a small ground plane which is only 35.5 mm × 60 mm. Multi-resonant operation is achieved by one radiator which is comprised of two branches and a floating coupled element on the back side of the substrate. The achieved bandwidth of the proposed antenna covers nine wireless standards such as GSM, GPS, DCS, PCS, UMTS, Bluetooth, WLAN, WiMAX 2.5 GHz and WiMAX 3.5 GHz. Antenna parameters are presented to validate the proposed antenna. Low profile design is very suitable for multiband mobile communication systems.