Arteriograms were reviewed in 60 cases of renal transplant dysfunction and correlated with the final diagnosis. Angiographic refinements included selective injections, 2-4X direct magnification, and flow-dependent injection rates. Angiography permitted recognition of common causes of post-transplantation dysfunction, including acute vasomotor nephropathy (AVN), acute refection (AR), chronic rejection, and obstruction of the ureter, renal artery, or renal vein. In 28 patients with AVN or AR who had technically adequate cortical microangiograms, classification was correct in 57%, indeterminate in 36%, and erroneous in 7%. In addition to its diagnostic value, angiography provides some prognostic information in AR, permitting prediction of functional return when the pattern suggests AVN and lack of return when cortical necrosis is indicated.