Abstract: Mast cell leukemia is a rare variant of mastocytosis, accounting for less than 1% of all mast cell disease and pose one of the greater challenges in the management of these patients, with a grave prognosis. Diagnosis of this neoplasm rests on the detection of abnormal mast cells in marrow and subsequent spill over to the peripheral blood. We report a case of aleukemic variant of mast cell leukemia in a pediatric patient, presenting with fever and chest pain for 10 days. The peripheral smear showed a picture of pancytopenia with abnormal/ atypical lymphoid cells. Bone marrow aspirate showed dense aggregates of atypical, hypogranular and partially degranulated mast cells expressing toluidine blue and CD117 positivity.