A 12 year old patient was treated for Sturge-Weber syndrome with choroidal haemangioma and total exsudative retinal detachment. The diagnosis was supported by echography and thin-layer computed tomography. Because of the exsudative retinal detachment photocoagulation could not be performed. Treatment by percutaneous radiotherapy with Caesium 137 was performed. The retina was reattached by application of 30 Gray. A flat pigmented scar developed in the area of the haemangioma at the posterior pole of the eye. No side effects appeared. The follow-up time is 26 months.