Objective: To develop a technique that would allow us to cannulate repeatedly the ophthalmic artery of young children with advanced retinoblastoma, to find a dose of melphalan that would be tolerable and tumoricidal for retinoblastoma when given intraarterially, and to study the local ocular and systemic side effects of intraarterial melphalan in these children. Design: Phase I/II clinical trial. Participants: Ten children with advanced retinoblastoma (Reese-Ellsworth V) eyes who were indicated for enucleation were entered into an institutional review board-approved protocol of ophthalmic artery infusion of melphalan to avoid enucleation. Methods: Cannulation of the ophthalmic artery was performed by a femoral artery approach using microcatheters while the children were under anesthesia and anticoagulated. Chemotherapy (melphalan) was infused into the artery over a 30-minute period. Main Outcome Measures: Ophthalmic examinations, retinal photography, and electroretinograms were used to document local toxicity, whereas physical examinations and complete blood counts were used to measure systemic toxicity. Results: The ophthalmic arteries were successfully cannulated in 9 cases (total, 27 times), as many as 6 times in 1 patient. Dramatic regression of tumors, vitreous seeds, and subretinal seeds were seen in each case. No severe systemic side effects (sepsis, anemia, neutropenia, fever, or death) occurred. No transfusions were required (red cells or platelets). Three patients developed conjunctival and lid edema that resolved without treatment. There was no toxicity to the cornea, anterior segment, pupil, or motility. One (previously irradiated) eye developed retinal ischemia; another eye had no toxicity after intraarterial chemotherapy but did develop a radiationlike retinopathy after brachytherapy. Vision stabilized or improved in all but 1 patient after treatment. Electroretinograms were generally poor (advanced eyes were treated), but in 2 cases, the electroretinogram improved after treatment (and resolution of a retinal detachment). Seven eyes avoided enucleation. Two intraarterially treated eyes were enucleated, with no viable tumors identified pathologically. Conclusions: We developed a technique of direct ophthalmic artery infusion of melphalan for children with retinoblastoma. The technique had minimal systemic side effects (one patient had grade 3 neutropenia) and minimal local toxicity. Among the first 9 cases treated with this technique, 7 eyes destined to be enucleated were salvaged.