The paper presents the influence of oregano extract (Origanum vulgare L.) on growth of Aspergillus versicolor, Emericella nidulans, Eurotium herbariorum, E. amstelodami, E. chevalieri and E. rubrum - producers of sterigmatocystin (STC) isolated from salads. Antifungal tests were performed by agar plates method. The composition of the active component of extract was determined by GC-MS method and the major components were: carvacrol (34.20%), triacetin (22.91%), carvone (18.05%), p-cymene (8.05%) and thymol (3.74%). The examined extract showed the ability to reduce mold growth at all applied concentrations. Minimum inhibitory concentrations (MIC) for E. nidulans, E. chevalieri and E. amstelodami were 2.5% (v/v) and over 2.5% (v/v) for A. versicolor. At 1.5% (v/v) concentration the extract completely inhibited the growth of E. rubrum, whereas higher dose of 2.5% (v/v) was fungicidal against E. herbariorum. Besides its sensory role in food products, the examined oregano extract also exhibits antifungal activities against producers of STC.