The aim of this study was to estimate safety of specific immunotherapy to insects' venom. The frequency of side effects was compared in two groups of patients: subjects with hypersensitivity to insects' venom only and patients with allergy to other allergens. In the examined group of 32 patients with Hymenoptera venoms allergy skin prick tests with common aeroallergens were performed in 30 subjects. In 18 patients (60%) at least one test was positive. In 23 patients (71.9%) immunotherapy with Hymenoptera venom was connected with side effects observed just after administration of vaccine. They were mainly local reactions (itching, redness and oedema). In 6 patients late reactions were observed. No correlation has been found between frequency of side effects of immunotherapy and positive results of skin prick tests. However systemic reactions were revealed only in the group of patients with at least one positive result of skin prick tests.