We report the development of Propionibacterium acnes endophthalmitis following Nd:YAG laser posterior capsulotomy. The patient previously underwent uncomplicated extracapsular cataract extraction with intraocular lens insertion and was free of inflammation prior to laser capsulotomy. Diagnostic vitrectomy and aqueous tap were performed, and P. acnes was isolated from the aqueous in thiol broth media after nine days of incubation under anaerobic conditions. The patient was managed with topical and systemic antibiotics and steroids. Complete resolution of inflammation with return of vision to 20/25 was achieved without removal of the intraocular lens or lenticular remnants.