Background: Hepatosplenic T-cell lymphoma (HSTCL) is a rare subtype of peripheral T-cell lymphoma. Patients usually present with splenomegaly and pancytopenia but without lymphadenopathy. Immunohistochemistry (IHC) staining of bone marrow biopsy shows intra-sinusoidal infiltration of CD3 and CD56 T-lymphocytes. Current treatment strategy of HSTCL includes a CHOP regimen (cyclophosphamide, adriamycine, vincristine, prednisone) followed by autologous transplantation. Case: A 28-year-old male presented with abdominal fullness, weight loss, and massive splenomegaly. Laboratory findings revealed pancytopenia. A CT scan of the abdomen displayed hepatomegaly and massive splenomegaly. The bone marrow pathology examination showed monotonous medium-sized lymphocytes with some cluster of atypical lymphocytes with loosely condensed chromatin and pale cytoplasm. The intra-sinusoidal location was more prominent after using IHC staining of CD3 and CD56, which are characteristics of HSTCL. We administered CHOP-based regiment every 3 weeks for 3 cycles; however, the response was a stable disease. Since the splenomegaly was still massive and compromised the patient, the multidisciplinary team decided to perform splenectomy. Unfortunately, the patient did not survive the surgery. Conclusion: Hepatosplenic T-cell lymphoma is a rare aggressive disease, which is part of peripheral T-cell lymphoma. CHOP-based chemotherapy appeared to be ineffective, and we need further studies to find the optimal treatment of HSTCL. © 2023, Czech Medical Association J.E. Purkyne. All rights reserved.