Sustained release of carmustine (1,3-bis[2-chloroethyl]-1-nitrosourea, or BCNU) via an episcleral implanted silicone device was used to treat Greene hamster melanoma implanted in the anterior chamber of rabbit eyes. Group 1 animals received carmustine intravenously; group 2 received the drug by local sustained release via an episcleral implanted silicone device; group 3 received the drug by both local sustained release and intravenous injection (a total dosage more than twice that in group 1); and group 4 was not treated. The effectiveness of the various administration routes was compared by clinical observation of tumour size and systemic and local toxic reactions, and by histopathological examination. Carmustine delayed the growth of Greene melanoma in all 3 treated groups, but was most effective when a lower dose of the drug administered intravenously was combined with an additional higher dose administered by local sustained release. Local side effects included corneal clouding and conjunctival oedema and congestion at the early stage of local drug delivery via the episcleral implanted device.