We tested if the sympathetic nervous system stimulates renal medullary renin and NADPH oxidase (NOX) activity in a synchronized manner and if in vivo NOX inhibition reduces renal medullary renin activity. Newborn Lewis rats were sympathectomized, sham- or apocynin-treated and fed a 0.60 % NaCl diet. In sympathectomized animals renal medullary renin activity was 1659 ± 394 ng Ang I/h*mg protein vs. 2749 ± 483 ng Ang I/h*mg protein in sham-treated animals (p < 0.05) accompanied by a 50 percent reduction in renin gene expression. Apocynin-treatment was without significant effect on medullary renin. Renal medullary NADPH oxidase activity was not significantly affected by neonatal sympathectomy. In sympathectomized animals medullary NOX1 mRNA expression was reduced by 50 percent, while NOX2, NOX4 and p47phox expression were not significantly different between groups. We conclude that the sympathetic nervous system activates medullary renin activity and gene expression and therefore stimulates the paracrine renin angiotensin system in the rat kidney. Our data suggest that NOX-dependent oxygen radical formation is not critical for the regulation of medullary renin activity in normotensive rats on standard rodent chow.