This study reported 2 new patients and 16 historical cases with pathologically proven intraocular infiltration with adult T-cell leukemia and lymphoma (ATLL) to know the timing of intraocular infiltration in the disease course. The first case was a 67-year-old woman who developed bilateral vitreous opacity about half a year after the onset of acute type of ATLL that had been unresponsive to chemotherapy. She underwent vitrectomy combined with cataract surgery in both eyes. She had bilateral optic disc atrophy and localized retinal white infiltrates in both eyes. Cytological examination of vitreous aspirates demonstrated medium-sized cells with aberrant flower-like convoluted nuclei, positive for CD3, and thus indicative of T-cells. The second case was a 38-year-old man who was diagnosed acute type of ATLL at the presentation of acute kidney injury. About half a year after initial chemotherapy and allogeneic hematopoietic stem cell transplantation, he developed aqueous hypopyon in the right eye, concurrent with cutaneous and central nervous system relapse. Aqueous tap disclosed class V abnormal cells. The aqueous "pseudohypopyon" resolved in response to another round of chemotherapy with mogamulizumab. In review of 18 patients, intraocular infiltration with ATLL was diagnosed by vitrectomy in 9, aqueous tap in 3, chorioretinal biopsy in 3, and autopsy in 3. The intraocular infiltration developed concurrently with systemic diagnosis of ATLL in 5 patients, but developed later after chemotherapy in 13. In conclusion, intraocular infiltration with ATLL appears rare, and pathological diagnosis by vitrectomy and aqueous tap would help determine therapeutic plan in relapse after chemotherapy.