The clinicopathologic correlation of two patients with primary intraocular lymphoma is described, both of whom had a rare and unusual presentation of hypopyon uveitis. Sampling of aqueous fluid proved the cytopathologic diagnosis of B-cell lymphoma in the first patient. In the second patient an iris biopsy confirmed a T-cell lymphoma. The samples were examined using haematoxylin and eosin, and immunohistochemical stains. These patients were diagnosed with primary intraocular lymphoma on initial presentation with hypopyon uveitis. Secondary glaucoma was noted in the patient with T-cell lymphoma. Both cases appeared confined to the eye and initially responded favourably to aggressive chemotherapy and radiotherapy, but later went on to develop systemic involvement. Clinicians should be aware of this dramatic mode of presentation, which is unusual for ocular lymphoma.