The Wolff-Parkinson-White syndrome or its variant, the pre-excitation syndrome, are described in about 1.2 per 1000 of the population, so the anaesthetic management of patients with this syndrome is important. Our experience is reported in 15 elective operations on seven patients with pre-excitation syndrome. The most significant feature is the occurrence of variation of the morphology of QRS complexes. Rhythm disturbance most commonly encountered is supraventricular tachycardia, but different cardiac arrhythmias may occur and sometimes these are fatal. In our study, major complications or cardiac arrhythmias did not occur. With regard to the anaesthetic technique, care should be taken not to produce tachycardia. Atropine is not absolutely contraindicated for premedication. Preoperative use of propranolol or of quinidine is questionable.