Intracytoplasmic delivery of oligonucleotides (ODN) can improve ODN-based strategies such as the antisense approach and the use of immunostimulatory CpG dinucleotide containing ODN. Shock waves are established for the treatment of nephrolithiasis and other diseases. Here we describe the use of shock waves as a new physical method for the direct transport of antisense ODN into the cytoplasm and the nucleus of cells. Human peripheral blood mononuclear cells together with antisense ODN were exposed to shock waves generated by an electrohydraulic lithotripter. ODN uptake was examined by flow cytometry and fluorescence microscopy. By optimization of physical parameters we achieved the transfer of high amounts of ODN which were detected within less than 5 min after shock wave exposure, with viability of cells higher than 95%. Transfection of human peripheral blood mononuclear cells with an antisense ODN directed against tumor necrosis factor (TNF) alpha resulted in a reduction in lipopolysaccharide-induced TNF production by 62% (n=5, P=0.006). Specificity of TNF suppression was confirmed with a four-mismatch oligonucleotide. Positive atmospheric pressure abolished antisense-mediated inhibition of TNF synthesis by blocking shock wave-induced cavitation and formation of oscillating air bubbles. Electroporation was less effective. The use of shock waves is thus an efficient physical tool for ODN delivery to cells. Shock waves may allow the evaluation of target proteins in cell types difficult to transfect with other methods and thus may improve the antisense technique for the analysis of unknown genes.