In three consecutive cataract operations, chlorhexidine was inadvertently used as an intraocular irrigating solution as a result of inattentiveness of an assistant. In two of the three patients, corneal endothelium damage was so severe that penetrating keratoplasty had to be performed. Further effects included pronounced iris atrophy, anterior chamber applanation, and a retrocorneal membrane. In one case, an increase in intraocular pressure developed. No effects were observed in the retina or optic nerve. Inadvertently using chlorhexidine for intraocular irrigation has far-reaching consequences for the affected eye and is recognizable by streak formation in the anterior chamber when intraocular infusion is initiated. To avoid such mistakes, the markings of the two bottles should be of different colors.