Abstract In order to evaluate the central origin of the hypertensive response to eserine, the neuronal efferent activity in the cervical sympathetic of the rat was investigated. It was found that eserine (100–400 μg/kg) produced a significant and dose-dependent increase in the neuronal activity in the preganglionic fibres of the cervical sympathetic nerve. Duration of the increased neuronal activity corresponded well to the duration of the hypertensive response to eserine. Atropine completely blocked the increased preganglionic neuronal activity produced by eserine. Methyl-atropine-, phentolamme-, hexamethonium- and reserpine-pretreatment did not affect the eserine effect. It is concluded that adrenergic activation by eserine is probably preceded by the activation of cholinergic mechanisms in the brain, leading to an increased efferent activity in the cervical sympathetic system.