The captopril renogram test has been shown to be a sensitive test for the diagnosis of renal artery stenosis in native and transplanted kidneys. Most reports have involved only stenosis of the main renal artery. Although segmental renal artery stenosis has been diagnosed successfully in native kidneys, it is not clear whether the captopril renogram test can diagnose segmental renal artery stenosis in a transplanted kidney. The authors report two cases of successful identification, by the captopril renogram test, of functionally significant stenosis in an intrarenal branch of a single transplant renal artery.