When aortic dissections extend to the renal arteries, reductions in renal blood flow can cause marked increases in renin production. The resultant rise in angiotensin II can lead to difficult‐to‐control blood pressure, despite normal postdissection antihypertensive agents. We highlight a case of a postdissection patient with malignant hypertension refractory to eight different enteral antihypertensives. Angiotensin‐converting enzyme inhibitors and angiotensin receptor blockers had been held due to postoperative acute kidney injury. A single dose of valsartan, administered on day 12, produced a marked drop in blood pressure, alleviation of encephalopathy, and allowed for cancellation of a planned tracheostomy. A serum renin level was found to be 50 times the normal upper limit. In patients with aortic dissection and renal artery involvement, angiotensin‐modifying agents may warrant earlier administration to combat this unique cause of hypertension.