Introduction: Iris melanoma accounts for 8% of uveal melanomas. Iris melanoma has some clinical differences in children in comparison with adult patients: smaller tumor size, less tumor seeding in iridocorneal angle, besides it is far less likely to cause secondary glaucoma. In children and adolescents it manifests as brown nodule, with better prognosis compared to adults due to earlier detection and smaller size of tumor. Case report: 12-year-old boy was admitted to Department of Pediatric Ophthalmology in Bialystok, due to the nodule of the iris in OS, which was present from the birth, but this change has recently begun to began to enlarge. Necessary diagnostic test were preformed such as slit-lamp examination, UBM, AS-OCT, gonioscopy and tonometry and next the patient was referred to Clinic of Ophthalmology and Ocular Oncology in Krakow with suspected iris melanoma. Earlier diagnosis was confirmed (stage T1aNxMx) and the boy received Ru-106 brachytherapy. The apliccator Ru-106 was sutured to the cornea and sclera of the left eye, and it was removed after two days - these procedures were performed in general anesthesia. There were no intra- and post-operative complications. During the last follow-up, 8 months after procedures, the patient has full visual acuity, clear lenses and normal intraocular pressure. The patient remains under strict oncological and ophthalmological control. Conclusions: Ruthenium-106 brachytherapy offers an effective and safe way of treatment for iris melanoma, with an and acceptable level of maintained visual acuity in the treated eye.