Mast cells are supposed to influence the growth of neurofibromas, because some of their mediators may also act as growth factors. Accordingly, mast cell stabilizers are claimed to reduce proliferation and itching of neurofibromas. Therefore, we quantified the mast cells of 19 neurofibromas and compared them with normal skin. We saw a statistically significant increase in mast cells in neurofibromas versus normal skin. However, there is no correlation between the age of neurofibromatosis (NF) patients and mast cell density. In our study the density of mast cells in neurofibromas is also independent of NF type, age of neurofibroma and chronic ultraviolet exposure in contrast to normal skin. Different tumors of the same patient had similar mast cell counts.