We studied six cases of chronic, indolent intraocular inflammation that occurred after extracapsular cataract extraction and posterior chamber intraocular lens implantation. The inflammation was characterized by a delayed onset, and in three cases had the clinical appearance of a granulomatous iridocyclitis. Cultures of intraocular specimens obtained from six eyes yielded Propionibacterium; five yielded P. acnes. Pleomorphic gram-positive bacilli consistent with Propionibacterium were identified in cytologic or histopathologic studies in four of the six culture-positive cases. After surgical and medical therapy, the inflammation resolved. Postoperative Propionibacterium endophthalmitis may masquerade as a chronic iridocyclitis.