Abstract: Sonodynamic therapy is the ultrasound dependent enhancement of the cytotoxic activities of certain drugs called sonosensitizers. The study of therapeutic efficacy of ultrasound is always preceded by in-vitro tests. In this work, two in-vitro sonication procedures were compared. One with the transducer positioned bellow the cell colony, radiating upward, with standing wave reflected from the water-air surface, the second, in the free field conditions. Efficiency of the cancer cells necrosis caused by ultrasound was compared with acoustical field intensity I SPTA measured by a hydrophone. The standing wave conditions effectively increased the intensity of the ultrasonic wave at the level of cells. To achieve 50% of cell viability, the intensity I SATA , decreased from 5.8 W/cm2 to 0.3 W/cm2 . In summary, sonication in the standing wave conditions can effectively and reproducibly destroy cells by ensuring the sterility and without the risk of overheating.