BACKGROUND/AIMS/METHODS: Aggressive systemic mastocytosis (ASM) is a subtype of systemic mastocytosis, which comprises a heterogenous group of disorders characterized by infiltration of bone marrow, skin, liver, spleen, lymph nodes and gastrointestinal tract by neoplastic mast cells. There is lack of data on the association of ASM with renal involvement, as kidney is not among the known organs affected by ASM.RESULTS/CONCLUSIONS: To the best of our knowledge, this is the first case of ASM associated with mesangioproliferative glomerulonephritis and monoclonal gammopathy of undetermined significance, without the presence of nephrotic syndrome. The patient's clinical course and the intriguing family history, along with the treatment selection are described. Finally, the proposed possible pathophysiological mechanisms explaining the renal involvement of our patient are discussed.