A novel light-weight multi-channel multi-wavelength ultra-low power near infrared spectroscopy (NIRS) system was designed and tested. The NIRS system was designed for clinical use to emit low power (maximum 5 mW) red and near infrared (NIR) light into human tissue and acquire, record, and display reflected light from various tissue depths. In this paper, results of initial functional tests of the system are presented. Potential clinical applications of the NIRS system include long-term non-invasive monitoring of functional activity in tissues, oxygen consumption in skeletal muscles, and tissue blood perfusion.