Electrical stimulation of the parasympathetic innervation to parotid or submandibular gland for 30 or 60 min resulted in increased [3H]thymidine uptake of both glands when measurements were made 18 h later. With 30 min of stimulation, the mean increase in parotid was 30% compared with unstimulated mates, and after 60 min of stimulation, the increase was 76%. Stimulation for 30 min with the adrenergic antagonists propranolol and phenoxybenzamine present showed an increase in [3H]thymidine of 76%. Stimulation of the chorda tympani for 30 min resulted in a mean increase of 59% in thymidine uptake of the sympathectomized submandibular gland compared with the unstimulated sympathectomized mate. beta-1,4-Galactosyltransferase activity of both stimulated parotid and submandibular glands also showed an increase of 71%. On the basis of the composition of the saliva in the oral cavity, we confirmed the identity of the stimulated nerve to parotid gland as the parasympathetic (auriculotemporal). Na, K, and amylase concentrations resembled closely the composition of saliva obtained directly from the duct with electrical stimulation of the parasympathetic nerve. These data provide the first evidence that electrical stimulation of the parasympathetic nerve to parotid and submandibular glands causes a mitogenic response in each of these organs; the data also provide the first evidence that electrical stimulation of the parasympathetic nerve causes an increase in levels of the enzyme beta-1,4-galactosyltransferase, known to be implicated in hyperplastic responses.