Though immediate pain is reported by nearly all patients undergoing needle-EMG, little is known about its cardiovascular risk from changes in blood-pressure or heart-rate. This study was thus conducted to investigate if, and to which degree, blood-pressure and heart-rate are influenced by needle-EMG. In 50 patients, 24 women, 26 men, aged 26-78 years, conventional needle-EMGs from 54 muscles were recorded. Pain was assessed on a verbal analogue pain-scale (1-10) and blood-pressure and heart-rate were measured before, during and after EMG. Mean pain-ratings before, during and after EMG were 0.8, 4.1 and 1.0, respectively. Mean systolic/diastolic blood-pressure was 144/87 mmHg before, 145/86 mmHg during and 144/87 mmHg after EMG. Mean heart-rate before, during and after EMG was 77, 77 and 78 beats/min, respectively. Systolic/diastolic blood-pressure increased above 145/85 mmHg in only 2/6 patients during EMG. The weak affection of blood-pressure and heart-rate by pain from needle-EMG was found in patients with and without hypertension. Mean blood-pressure, heart-rate and pain-ratings before, during and after EMG were independent of age, sex and muscle. The correlation between pain-ratings and blood-pressure and heart-rate was not significant. This study shows that needle-EMG moderately hurts but does not increase blood-pressure or heart-rate, irrespective of known arterial hypertension. Based upon these findings, the cardiovascular risk of needle-EMG from changes in blood-pressure or heart-rate is regarded negligibly low.