BACKGROUND Spinal cord stimulation (SCS) has been used in the treatment of severe angina pectoris since the 1980s. Several studies have shown both an antianginal and an anti-ischaemic effect. There are several theories about the mechanism behind the anti-ischaemic effect of SCS, including the possibility that it is dependent on an increase in coronary flow velocity. OBJECTIVE To determine if there were effects of SCS on coronary flow velocity during cardiac stress. METHODS Eight patients with severe anginal pain secondary to coronary artery disease who had been implanted with an SCS device were included in the study. In addition, four patients with syndrome X were examined. If possible, a Doppler guidewire was placed in the vessel corresponding to the ischaemic area revealed on a prior myocardial scintigram. A temporary pacemaker electrode was placed in the right atrium. Atrial pacing started at 80 beats/min and increased by 10 beats/min every 2 min until the patient experienced moderate angina; the pacing frequency was then maintained at the same level. After 2 min of pacing at this frequency, SCS treatment commenced; after a further 5 min, pacing was stopped. Throughout the procedure, coronary flow velocity, assessed as average peak velocity (APV), was monitored continually. RESULTS APV increased during pacing in all the patients with coronary artery disease (mean increase 53%; P < 0.02). There were no significant changes in APV during maximum pacing frequency when stimulation was introduced. CONCLUSIONS The results of this study do not support the theory that the anti-ischaemic effect of SCS is dependent on an increase in coronary flow velocity.