Systemic Mastocytosis (SM) has not previously been reported in association with minimal change disease (MCD). Mastocytosis is a rare myeloproliferative disease that is characterised by uncontrolled proliferation of aberrant mast cells. This can lead to a wide variety of symptoms and can present as either a cutaneous or a systemic disease. Systemic manifestations usually include bone marrow, intestine, liver and splenic infiltration of mast cells, with reports of renal manifestations being rare. This is a case report of a 70-year-old man who was known to have Systemic Mastocytosis and who presented with nephrotic range proteinuria. Renal biopsy diagnosed Minimal Change Disease with mast cell infiltration being an identified by C-kit staining. The patient was treated with steroids and is currently in remission of the proteinuria.