Tunable diode laser spectroscopy (TDLS) is proposed for content measurements of trace gases like CO, carbon-dioxide, NH3, CH4, NO, NO2 in human and animal's exhalation. High sensitivity and wide dynamic range of the method ensure fast detection of these gases at ppb level and within the accuracy better than 10%. One-expiration sample is enough to reach these parameters. There is no need for any preliminary preparations of tested samples. Some pairs of the gases, for instance, CO and carbon-dioxide, NH3 and carbon- dioxide, or CO and nitrous oxide, can be measured simultaneously by one laser providing complex studies. The high sensitive gas analysis could provide necessary background to the noninvasive diagnostics in a wide variety of medical problems. Perspectives of the TDLS methods in application to medicine diagnostics are demonstrated by the first results of exhalation tests.