Xanthogranulomatosis is a multicentric or systemic proliferative disorder of histiocytes. Two cases of xanthogranulomas are reported, each involving the kidneys. One patient also had concomitant orbital and CNS involvement. Primary renal involvement without associated retroperitoneal masses is an uncommon manifestation of this disorder. The CT appearance of renal involvement in both patients was distinctive and remarkably similar. Both patients had bilaterally enlarged kidneys in which the renal sinus fat was replaced by a fibrotic process that caused mild calicectasis. The clinical and roentgenographic features of xanthogranulomatosis bear a close resemblance to those seen in two fibrosclerosing syndromes: sinus histiocytosis with massive lymphadenopathy and retroperitoneal fibrosis.