A systematic review of 27 reports of endophthalmitis outbreaks following cataract surgery between 1985 and 2011 found the 2 most common causes associated with the outbreaks were contaminated solutions, 10 reports (37%), and contaminated phacoemulsification machines, 6 reports (22.2%). Other possible sources of contamination included ventilation systems, 3 (11.1%); defective sterilization, 3(11.1%); miscellaneous, 3 (11.1%); in 5 outbreaks (18.5%), no possible source could be identified. Bacteria occurred in 23 outbreaks (85.2%) and fungus in 4 (14.8%). Causative organisms were gram-negative bacteria, 15 (65.2%); gram-positive bacteria, 5 (21.7%); and both gram-positive and gram-negative bacteria, 3(13.1%). Pseudomonas aeruginosa was causative in 14 of 27 (51.8%) gram-negative bacteria. After treatment in 229 patients, a visual acuity outcome of 20/400 or better was achieved in 127 patients (55.5%). Outbreaks of endophthalmitis following cataract surgery are often caused by gram-negative organisms and can be associated with poor visual outcomes. In this review, the most common source was irrigation solutions used perioperatively.