Therapeutic outcome of patients suffering from malignant melanomas of the conjunctiva. Eighty-one cases of conjunctival melanoma treated between 1960 and 1988 were studied to determine factors that might affect outcome in patients with such lesions. The therapeutic procedures performed were local excision (16), local excision followed by brachytherapy with Sr-90/Y-90 (32), local excision followed by cryotherapy with liquid nitrogen (16), brachytherapy with Sr-90/Y-90 (12), local excision followed by external beam irradiation (3), and local excision followed by brachytherapy and cryotherapy (2). The median follow-up period was 5.5 years (longest 26, shortest 1 year). Sixty two patients (76.5%) showed a complete regression of the melanoma, 19 (23.5%) developed recurrences, and 15 (18.5%) died from metastases. The melanomas had developed with almost equal frequency from a pre-existing naevus (25.9%), from primary acquired melanosis (25.9%), and 'de novo' (30.9%). Small tumours had a higher chance of regressing (80.6%) than larger ones (68.6%). The cumulative survival rate was 76% after five years and 60% after 10 years from any causes of death and 87.6% after five years and 76.3% after 10 years from deaths caused by metastases. Most deaths from metastases occurred within 5 years. At 88.5%, the cumulative survival rate of patients with small tumours (less than one quadrant of the bulbar conjunctiva and less than 2 mm thickness) was significantly higher than that of patients with larger tumours (more than one quadrant of the bulbar conjunctiva and/or more than 2 mm thickness) with 65% after eight years. Local excision followed by beta ray irradiation (Sr-90/Y-90) or cryotherapy can be recommended as the treatment of choice. Nevertheless the behaviour of conjunctival melanomas remains unpredictable in individual cases. 