Rationale: T-cell large granular lymphocytic leukemia (T-LGLL) is a rare lymphoproliferative neoplasm of cytotoxic T cells and renal cell carcinoma (RCC) is the most common form of kidney cancer, but T-LGLL associated with RCC has never been reported. Patient concerns: A 58-year-old Chinese male presented with general fatigue and intermittent-remittent fever, accompanied by palpitations and dizziness. Diagnosis: Radical nephrectomy was performed, and a diagnosis of clear cell carcinoma (T1N0M0, I phase) was made based on the postoperative pathology findings. With typical cellular morphology, immunophenotype and T-cell receptor gene rearrangement, a diagnosis of T-LGLL was established. Interventions: After radical nephrectomy, this patient remained asymptomatic without any treatment. Outcomes: To date, the patient is generally in good condition, without complaints of discomfort. Lessons: The coexistence of these 2 entities may not be coincidental, and it is likely that they may share a common pathogenic pathway related to immune dysregulation.