BACKGROUND: The uveitis–glaucoma–hyphema (UGH) syndrome was first described in 1978 as a complication of anterior chamber polymethyl methacrylate intraocular lenses implantation. Introduction into practice of foldable intraocular lenses with intracapsular fixation has reduced the incidence of UGH. However, this complication still occurs today, especially with extracapsular intraocular lens fixation. AIM: The aim of this study is to describe “uveitis–glaucoma–hyphema” syndrome pathogenesis, clinical features, and diagnosis. MATERIAL AND METHODS: A retrospective analysis of medical data for 2017–2021 identified 100 patients (101 eyes) diagnosed with UGH syndrome, they made up the study group. Complaints, medical history, biomicroscopy, visual acuity and intraocular pressure were assessed. 37 patients underwent anterior segment ultrasound biomicroscopy using the Accutome UBM Plus (USA). RESULTS: The occurrence of UGH syndrome is at least 0.19%. The leading UGH syndrome risk factor was intraocular lens material. In 49% of cases these were AcrySof hydrophobic intraocular lenses. The second UGH risk factor was extracapsular (mixed and sulcus) intraocular lens fixation, occurring, according to ultrasound biomicroscopy, in 54 and 19% of cases, respectively. The most significant diagnostic UGH sign was hyphema (93%). Ocular hypertension was detected in 66%, and uveitis in 57% of cases. CONCLUSIONS: The main UGH syndrome manifestations are hyphema and iris transillumination after phacoemulsification complicated by posterior capsule rupture with extracapsular hydrophobic intraocular lens fixation. The most informative instrumental method to assess intraocular lens position is ultrasound biomicroscopy.