Mastocytosis is a clonal neoplastic disorder of the mast cells(MC) that can be limited to the skin(cutaneous mastocytosis) or involve one or more extracutaneous organs(systemic mastocytosis). The clinical manifestations of mastocytosis are heterogeneous ranging from indolent disease with a long-term survival to a highly aggressive neoplasm with survival of about 6 mo. Although liver involvement in aggressive systemic mastocytosis(ASM) is relatively common, the development of portal hypertension with or without cirrhosis is rare. We report a case of ASM without skin involvement in a 72-year-old caucasian male who presented with non-cirrhotic portal hypertension based on clinical, analytical, imagiological and endoscopic findings. Given the hematological picture, the correct diagnosis was established based on ancillary tests for MC using bone marrow aspirates and biopsy. Extensive involvement of the liver and gastrointestinal tract was histologically documented. The disease progressed rapidly and severe pancytopenia and recurrent upper gastrointestinal bleeding became the dominant problem. This case illustrates the challenge in establishing a diagnosis of ASM especially when the clinical picture is atypical and without skin involvement. Gastroenterologists should consider infiltrative disease, particularly systemic mastocytosis, as a differential diagnosis in a clinical case of portal hypertension of unknown etiology. The clinical manifestations of mastocytosis are heterogeneous ranging from indolent disease with a long -term survival to a highly aggressive neoplasm with survival of about 6 months. Although liver involvement in aggressive systemic mastocytosis (ASM) is relatively common, the development of portal hypertension with or without cirrhosis is rare. We report a case of ASM without skin involvement in a 72-year-old caucasian male who presented with non-cirrhotic portal hypertension based on clinical, analytical, imagiological and endoscopic findings. Given the hematological picture, the correct diagnosis was established based on ancillary tests for MC using bone marrow aspirates and biopsy . Extensive involvement of the liver and gastrointestinal tract was histologically documented. The disease progressed ra pidly and severe pancytopenia and recurrent upper gastrointestinal bleeding became the dominant problem. This case illustrates the challenge in establishing a diagnosis of ASM especially when the clinical picture is atypical and without skin involvement. Gastroenterologists should consider infiltrative disease, particularly systemic mastocytosis, as a differential diagnosis in a clinical case of portal hypertension of unknown etiology.