Investigation of the smaller of a pair of unequal kidneys showed a band of atrophy in the inner medulla, sparing the papillary tip, which was viable and contained collecting ducts. The kidney had extensive cortical atrophy with glomerulocystic disease and multiple tiny renal cell neoplasms. These changes were considered secondary to the medullary lesion. Study of 85 other kidneys taken a autopsy and surgery showed 8 other cases with similar band-like atrophy in the medulla to various degrees. All 9 cases had severe vascular disease. This asymmetrical or band-like atrophy of the renal medulla seemed to be fairly common but previously unreported, could be differentiated from renal papillary necrosis, and was most likely due to an episode of severe ischaemia, possibly in kidneys with pre-existing vascular narrowing.