In this chapter the working principles and the main application areas of the piezoquartz microweighing method, piezoelectric chemosensors and multisensor systems employed for gaseous phase analysis over the past 30 years are discussed. The advantages and challenges of the multisensor approach and “electronic nose” systems regarding single sensors are considered. Moreover, examples of piezoelectric “electronic nose” use for a wide range of analytical tasks, such as environmental monitoring, foodstuff quality assessment, medical and health care applications are reported in order to demonstrate multisensor approach effectiveness and to predict further development trends.