Objective. To study the characteristics of pilots' electrocardiogram during parabolic flight. Method. Dynamic electrocardiogram (DCG, CM1 and CM5 bipolar leads) were recorded in 13 pilots before, during and after parabolic flights. Result. Preflight and postflight values of heart rate (HR) and cardiac rhythm were essentially the same in all cases, but HR increased to a higher level of 86.0 +/- 7.3 bpm with maximum of 137.0 +/- 12.2 bpm, and minimum of 57.7 +/- 6.6 bpm during parabolic flights. During flights, one pilot's cardiac rhythm changed slightly and in another pilot T wave became inverted. In other two pilots, ST segments shifted downward more than 0.1 mV transiently. All these pilots showed negative result in maximal exercise on the ground. Conclusion. DCG could be used to evaluate the changes of cardiac electric activity during the whole parabolic flight.