The outcome is reported in 17 patients in whom an eye was enucleated for malignant melanoma of the choroid with extrascleral extension and who subsequently underwent adjuvant external beam radiotherapy to the orbit as the primary treatment of the extraocular spread of their tumour. Extrascleral extension was encapsulated in five, non-encapsulated in two, and had been surgically transected at enucleation in 10 cases. All the patients have been followed up from enucleation to the present day. Orbital recurrence occurred in only one patient. The overall actuarial survival rate was 51% at 5 years, 44% at 10, and 33% at 15 years. A low orbital recurrence rate of 6% compares very favourably with published figures for this event after enucleation for melanoma with extrascleral extension but without radiotherapy. Adjuvant orbital radiotherapy may have a place in the treatment of selected cases of extracleral extension of intraocular malignant melanoma.