1. Structural and functional changes resulting from baroreceptor denervation were studied in rabbits 4 days after surgery.
2. After section of the aortic and carotid sinus nerves, arterial pressure was characteristically labile although the mean pressures were not significantly different from those of control animals.
3. The responsiveness of isolated ear arteries and cephalic veins from deafferented animals to noradrenaline and electrical stimulation of their sympathetic innervation was similar in both groups.
4. Neuronal uptake of noradrenaline into arterial tissue was similar in both groups, although uptake into the cephalic veins of deafferented animals was less than in the control group.
5. [3H]Thymidine uptake, an index of DNA synthesis, was similar in both groups, radioautography revealing no difference in smooth muscle cell labelling.
6. Uptake of [3H]proline, an indicator of protein synthesis, by aorta, ear, brachial, basilar and renal arteries from deafferented animals was greater than in control animals.
7. Baroreceptor denervation altered protein metabolism in the arterial wall.