Purpose: Intravitreal chemotherapy for primary intraocular lymphoma (PIOL) increasingly is promoted as an alternative to radiotherapy, owing to putative high failure and complication rates of the latter modality. Our aim was to confirm whether these concerns about radiotherapy were borne out in patients treated at our institution over the last decade. Design: Retrospective interventional case series. Participants: A total of 21 eyes of 12 patients with PIOL. Methods: Comprehensive chart review of ophthalmologic and systemic manifestations, treatments, and outcomes. Main outcome measures: Radiation complications and local tumour control. Results: Cytology-confirmed lymphoma involved one eye in three patients and both eyes in nine patients. Initial treatment included external beam radiotherapy and chemotherapy (six patients), chemotherapy alone (four patients), radiotherapy alone (one patient), and no treatment (one patient). Ocular relapses occurred in no patients receiving radiotherapy and in two patients who did not receive radiotherapy. Complications of radiotherapy included dry eye (four patients), cataract (four patients), and mild radiation retinopathy (two patients). Conclusions: Radiotherapy for PIOL is highly effective with acceptable complications. In the absence of a clear advantage to intravitreal chemotherapy, which involves repetitive injections and associated risks, radiotherapy may still be the most appropriate first-line treatment in most cases.