Cataract surgery has become one of the commonest and safest procedures to be performed in ophthalmology departments across the UK. Optometrists and other health care professionals have become increasingly involved in post-operative care and it is essential that they are able to recognise and to respond to the rare complications resulting from this surgical procedure. Corneal oedema, raised intraocular pressure, corneal abrasion, wound leak, suture complications, iris prolapse, incarcerated vitreous, severe anterior uveitis and displacement of the intraocular lens may occur as early complications. Cystoid macular oedema, endophthalmitis, retinal detachment, posterior capsule opacification and unsatisfactory refractive error may arise as later complications. This article reviews the nature and appearance of each of these complications.