One major challenge today is to deliver effective and high-quality medical services while curbing growing costs of the healthcare at the same time. Automated wireless biopotential acquisition systems are an interesting part of the solution. Body functions of the patient can be monitored for long term to build personal clinical profile increasing treatment accuracy. There is a rising demand for high-quality, low-power, low-noise wireless biopotential acquisition systems for clinical and consumer applications. In these devices, front-end amplifier presents complicate design challenge because achieving sufficient noise levels usually require considerable power consumption. In this paper, a subthreshold nano-watt instrumentation amplifier for wireless ECG applications is introduced and simulated. The amplifier is designed in a standard 0.13µ CMOS process. The amplifier has a gain of 40dB, the input-referred rms noise voltage of 4,874uVrms (0,8-209Hz) and a NEF value of 5,8 while consuming only 100nW.