The "specific" investigations for sinus node syndrome (SNS) in 22 patients are analyzed. SNS was defined as sinusbradycardia below 40/min and sinus-standstill over 2 sec. Atropin (1 mg i.v.), exercise test and carotid pressure were of little help in establishing the diagnosis, while Holter monitoring and sinus-node recovery time were significantly abnormal in all patients investigated.