Introduction. Tryptase and histamine levels may serve as an indicator of mast cells stimulation related to various diseases, such as mastocytosis, IgE-related allergy, confirming their participation in the pathogenesis. Aim. Analyse tryptase and histamine levels and assess the correlation between tryptase and histamine levels in serum of the different groups of study patients. Material and methods. The determinations were performed in 14 mastocytotic patients, including 6 patients with the systemic mastocytosis and 8 with urticaria pigmentosa, in 14 with innate angio-motor oedema due to C1 inhibitor deficiency, and in 10 healthy controls. Tryptase levels were determined using PhadiaUniCAP TRYPTASE reagents. Histamine concentrations were measured using HISTAMINE ELISA kit (LaborDiagnostikaNord). Results. In 6 patients with systemic mastocytosis, the level of tryptase was high (>60 mu g/L). In the majority of the patients with urticaria pigmentosa, the level of tryptase was elevated, but it did not exceed 60 mu g/L. In half of the patients with systemic urticaria, the level of histamine was elevated, but it was not correlated with the increased level of tryptase. In the people with hereditary angioedema due to C1 inhibitor deficiency, the serum levels of tryptase and histamine were normal. In that group, no correlation was shown to occur between the levels of the study parameters. Conclusions. No correlation was found between tryptase and histamine levels. Thus, it seems reasonable to conclude that the mediators are released from the mast cells independently.