In addition to its involvement in reproduction, oxytocin (OXT) has roles in the regulation of feeding, water balance and blood pressure. Neurons in the dorsal vagal complex, which includes the nucleus of the solitary tract (NTS) and the dorsal vagal nucleus (DVN), are part of the neuronal circuitry regulating these latter functions. OXT-immunoreactive (IR) axons, which probably originate from the paraventricular nucleus of the hypothalamus, a centre for autonomic and neuroendocrine integration, occur in the dorsal vagal complex; but it has not yet been conclusively established which neurons in this region receive an OXT-IR innervation. To answer this question, we identified autonomic neurons in the dorsal vagal complex in two ways. In awake rats, we lowered blood pressure by intravenous administration of hydralazine (n = 6; Stornetta et al. 2001) or raised blood pressure with a 90 min intravenous infusion of phenylephrine (n = 12; Minson et al. 1997) to activate reflexly cardiovascular neurons in the nucleus of the solitary tract (NTS) and thereby evoke Fos expression. Seven rats were anesthetized (pentobarbitone, 60 mg kg^-1 i.p.) and neuromuscularly blocked (α-bungarotoxin, 150 μg kg^-1 i.v.) for juxtacellular labelling; blood pressure and heart rate were continously monitored and reflex responses to tail pinch were assessed regularly. In these rats, we identified and electrophysiologically characterised individual neurons in the NTS (n = 8) or DVN (n = 6) that responded to vagal stimulation and labelled them juxtacellularly with biotinamide. At the end of all experiments, rats were perfused with 4% formaldehyde under pentobarbitone anaesthesia (100 mg kg^-1 i.p.). Fos-IR nuclei and/or OXT-IR axons were revealed with a nickel intensified diaminobenzidine reaction (black); and choline acetyltransferase (ChAT)-immunoreactivity or biotinamide, with an imidazole-intensified diaminobenzidine reaction (brown). In all rats treated with hydralazine or phenylephrine, varicose OXT-IR axons formed a network around Fos-IR nuclei in the caudal and mid NTS and were associated with ChAT-IR neurons in the DVN. Six out of eight of the juxtacellularly labelled NTS neurons were closely apposed by at least one OXT-IR varicosity. All six labelled DVN neurons received close appositions on their proximal and distal dendrites but their cell bodies were too heavily labelled to detect appositions. These results suggest that oxytocin may directly affect the activity of both NTS neurons and preganglionic neurons in the DVN through inputs on their dendrites.