Computed tomographic studies of eight patients with proven renal tuberculosis demonstrated a spectrum of findings related to the extent and the severity of kidney involvement. In early or focal disease, obstruction of a single major calyx or a group of minor calyces was noted (four cases) with no excretion of contrast material into the affected calyces (three cases) and cortical thinning. Tuberculosis of the renal pelvis (five cases) was manifested by either pelvic dilatation secondary to ureteropelvic junction obstruction (three patients) or diffuse pelvic contraction (two patients). In far advanced disease (four cases) the kidneys were small and exhibited atrophy with replacement of parenchyma by one or more low density areas. Calcifications (37.5%) were identified in the parenchyma and within the calyces. Computed tomography may provide the first clue in suggesting the inflammatory nature of a renal mass and excluding a neoplastic process. Computed tomography is also of value in determining the full extent of extrarenal involvement and the amount of residual functioning parenchyma, both of which are critical in proper treatment planning.