Piezoelectric materials have direct and converse piezoelectric effects and can serve as actuators and/or sensors. A piezoelectric impedance technique for crack monitoring in concrete structures is addressed in this paper, which use the electromechanical coupling property of piezoelectric materials. The basic principle of the technique is that by measuring the electrical impedance of piezoelectric ceramic sheets (PZT) bonded to the surface of host structure, the changes in structural mechanical impedance resulted from the presence of crack damage are monitored because the electrical impedance of PZT is directly related to the mechanical impedance of host structure. The main features of the technique are that it is not based on any physical models and its high frequency characteristics. An experimental study on crack monitoring of concrete beams was implemented based on the piezoelectric impedance technique. In this experiment, the electrical admittances (inverse of electrical impedances) of PZT were measured when the host beam was suffering from cracks with variable depth. Subsequently, a damage index, the root-mean-square deviation of real admittance (RMSDR) was presented, by which the locations and extents of concrete cracks were determined. It was found experimentally that the piezoelectric impedance technique for crack monitoring in concrete beam was quite effective and sensitive, which indicated its favorable application views in civil infrastructure systems.