Primary intraocular lymphoma (PIOL) treatment in the absence of other involvement of the central nervous system is controversial. We evaluated the outcome of ocular radiation therapy (RT) alone in 18 patients with PIOL who had no imaging evidence of brain or meningeal involvement, treated from 1999 to 2011. Median age at diagnosis was 64 years (range 32-82). Median follow-up was 25 months. Eleven had bilateral ocular involvement. All received external-beam orbital RT to a median dose of 36 Gy. Twelve patients received ocular RT alone; seven remain relapse-free at a median follow-up of 30 months. Five experienced brain or eye recurrence and were effectively salvaged with chemotherapy ± RT. Six patients received chemotherapy before ocular RT; three relapsed and received salvage therapy. Overall survival (OS) at 2 years was 94%. Two-year freedom-from-relapse was not different between the groups. Ocular RT alone resulted in excellent ocular control of PIOL, and relapses were effectively salvaged.