Previous studies have found inflammation, in particular T lymphocytes, to be a contributing factor in the genesis of various forms experimental hypertension (1,2). Currently, clinical interventions such as renal denervation (RD) and carotid body denervation (CBD) are aimed at targeting the autonomic nervous system to treat hypertension (3). However, the effects of these blood pressure lowering strategies on the immune system are unknown. In the current study, RD and CBD was performed in the spontaneously hypertensive rat (SHR) and flow cytometry used to examine tissue infiltration of T lymphocytes (CD3+) in the aorta and brainstem. All procedures conformed to the UK Home Office guidelines on animals (Scientific Procedures) Act 1986 and were approved by the University of Bristol’s Animal Ethic Committee. Rats were anaesthetised with ketamine (60 mg kg−1; i.m.) and medetomidine (250 μg kg−1, i.m.) and aseptic techniques used. Bilateral RD was achieved via a retroperitoneal incision to exposure of the renal artery. The nerves and adventitia were stripped from the renal artery and renal plexus, which were then painted with a dilute (10%) phenol solution. For CBD, the CB was visualised and branches of the carotid sinus nerve sectioned. Surgical sham-operated SHR (SS) rats underwent the same surgical procedures to expose the kidney and CB but the nerves were left intact. Compared to the SS group, arterial pressure and renal sympathetic nerve activity in the SHR was significantly lowered following both RD and CBD (see abstract by W. Pijacka et al). The percentage of infiltrating CD3+ T lymphocytes in the brainstem (9.6 ± 0.7 vs 6.4 ± 0.8%; t(9) = 2.79, p < 0.05) as well as the aorta (14.5 ± 1.6 vs 10.0 ± 1.1%; t(16) = 2.18, p < 0.05) were significantly reduced following RD. Following CBD, there was a trend toward reduced percentage of CD3+ cells in the aorta (t(13) = 1.36, p = 0.19) but unlike RD, there was no change in CD3+ cells in the brainstem. These data suggest that there is significant systemic CD3+ cell infiltration in the SHR and that some, but not all, procedures targeting the autonomic nervous system may have benefits in lowering tissue inflammation associated with hypertension. We strive to determine the causal relationship between reduced vascular inflammation and the anti-hypertensive effect of RD.