Intraocular lymphoma (IOL) is a rare lymphocytic malignancy which contains two main distinct forms. Primary intraocular lymphoma (PIOL) is mainly a sub-type of primary central nervous system lymphoma (PCNSL). Alternatively, IOL can originate from outside the central nervous system (CNS) by metastasizing to the eye. These tumors are known as secondary intraocular lymphoma (SIOL). The IOL can arise in the retina, uvea, vitreous, Bruch’s membrane and optic nerve. There are predominantly of B-cell origin; however there are also rare T-cell variants. Diagnosis remains challenging for ophthalmologists and pathologists, due to its ability to masquerade as noninfectious or infectious uveitis, white dot syndromes, or occasionally as other metastatic cancers. Laboratory tests include flow cytometry, immunocytochemistry, interleukin detection (IL-10: IL-6, ratio >1), and polymerase chain reaction (PCR) amplification. Methotrexate-based systemic chemotherapy with external beam radiotherapy and intravitreal chemotherapy with methotrexate are useful for controlling the disease, but the prognosis remains poor. Therefore, it is important to make an early diagnose and treatment. This review is focused on the clinical manifestations, diagnosis, treatment and prognosis of the IOL.