The worldwide success of extracorporeal lithotripsy and shock wave treatment of some orthopedic diseases is not doubted. In the future, shock waves could also be used as a method for in vivo drug delivery and gene transfer into target cells; however, basic research is still necessary to understand shock wave interaction with biological tissue, bacteria, and cells. The destructive effects of ultrasonic waves on micro-organisms and the reduction in renal infections after extracorporeal shock wave lithotripsy led to the idea of studying the effects of lithotripter shock waves on bacteria. Independent of possible applications to medicine, this could lead to a new, nonthermal food preservation method. The bactericidal effect of underwater shock waves on Escherichia coli ATCC 10536 and O157:H7, Listeria monocytogenes L8, and Salmonella enterica servovar typhimurium suspensions in isotonic saline solution were studied. Shock waves of about 55 MPa were generated using an electrohydraulic generator. Results indicate that pressure variations, shock wave-created cavitation, and the radiation resulting from the high-voltage spark significantly reduce the viability of these micro-organisms. An analysis of variance revealed that the bactericidal action of shock waves seems to depend on multiple-factor interactions, which vary depending on the type of bacteria.