AbstractNineteen patients with malignant uveal melanomas were treated with I‐125 applicators. There were 10 males and 9 females with a median age of 61 years (range 42–76). The tumour was located in the choroid in 12 eyes and in the choroid and ciliary body in 7 eyes. The size of the tumours was 7–18 mm in maximal basal diameter (median 12), 5–16 mm in minimal basal diameter (median 10), and 5.5–15 mm in thickness (median 8.5). The volume of the tumours was 123–1890 mm3(median 540). All tumours were classified as large (T3). For the irradiation, a computer program, which calculates three‐dimensional dose distribution of I‐125 seeds in gold plaques, was developed. By modifying the seed positions, activity and the orientation, patients can be treated individually. Iodine‐125 emits low energy photons, ideal for intraocular tumour therapy and tissue. Extra‐ocular tissue located behind the applicator can be completely shielded by a 0.5 mm gold layer. The dose at the apex of the tumour ranged from 30 to 120 Gy (median 93). The treatment time ranged from 44 to 600 h (median 235). Preliminary results are good. After a median follow‐up of 6 months, the tumour growth has been arrested in all eyes and in 10 eyes the tumour