The stimulation of the phrenic nerves in the neck is one of the techniques for the examination of diaphragmatic contractility. Current methods are restricted by their painful (transcutaneous stimulation) or even potentially dangerous nature (needle stimulation). We have tested both the feasibility and the validity of using magnetic stimulation (SMC) to stimulate the phrenic nerves. This method is painless and devoid of any side effects. Three healthy subjects have been studied using an EMG and transdiaphragmatic pressure measurements (Pdi.) Pdi values obtained by SMC (36.5 +/- 13.5 cm H2O) and their relation to maximal Pdi (22.6 +/- 7%) and to the Pdi at the time of maximal sniff-Pdi sniff (34.7 +/- 8%) were comparable to those values obtained using other methods and were reproducible. The preliminary results show that SMC is a technique for the study of the phrenic nerve and diaphragm which has the advantage of simplicity in use, is repeatable and is completely innocuous.