1. A male tetraplegic patient received electrical stimulation to cause penile erection. On one occasion blood pressure recorded by sphygmomanometer rose from 130/80 torr to 180/100 torr. On a subsequent occasion blood pressure and heart rate were continuously recorded using an arterial catheter. During stimulation, blood pressure rose from 110/65 torr to 255/110 torr- It is suggested that whenever such stimulation is used, blood pressure should be monitored continuously using similar methods.2. Plasma noradrenaline and plasma adrenaline were estimated during the resting stage and during stimulation. Plasma noradrenaline rose markedly, suggesting an increase in sympathetic nervous activity.3. Plasma Prostaglandin E and Prostaglandin F were estimated before and during stimulation. A large elevation in Prostaglandin E occurred. Its release could be a result of sympathetic nervous activity.