Correlated cHnical and pathologic studies on the renal insufficiency which frequently follows traumatic shock are presented, based on 60 fatal cases of battle injury. The constant clinical features are excretion of heme-contain-ing pigment in the urine, albuminuria, oliguria, azotemia, fixation of sp. gr. Inconstant, but usual, is mild hypertension. Histologic features develop in orderly sequence: lipid vacuolization of cells of ascending limbs, 18-24 hrs.; precipitation of pigment in lower nephron, 24-48 hrs.; necrosis of loop epithelium, 3 to 4 days; interstitial inflammation, 3 to 4 days; rupture of tubules, 4 to 5 days; extrusion of casts and granuloma formation, 5 to 6 days; venous thrombosis, 6 to 8 days. Two etiologic factors constantly present were excretion of benzidine-positive pigment in the urine and recovery from a state of shock. Renal insufficiency antedated all structural change but was never progressive in the absence of a pigment nephropathy.