This paper presents a dual mode CMOS low noise amplifier (LNA) suitable for WiMAX (Worldwide Interoperability for Microwave Access) applications, 2.4 GHz. The design concept is based on the novel idea of body biasing. Measurement results show that in the high gain mode, for VBS=0.3V, the cascode LNA, implemented in a 0.13μm CMOS standard process, exhibits a 14 dB power gain, a 3.6 dB noise figure (NF) and -4.6 dBm of third order intercept point (IIP3) for a 4 mA current consumption under 1V supply. Tuning VBS to -0.55V, switches the LNA into the low gain mode. It achieves 9 dB power gain, 6.2 dB NF and 11 dBm IIP3 under a constrained power consumption of 2 mW.