Zucchini is a very valuable vegetable, easy to grow both in the field and under covering, but it is affected by pathogenic fungi. The experiment was carried out at a farm near Lublin where three zucchini cultivars, ‘Astra Polka’, ‘Atena Polka F1’ and ‘Soraya’, were cultivated in a plastic tunnel and in the field in 2008-2009. The leaves, petioles and stems of zucchini were collected for laboratory tests. Mycological analysis showed that the predominating fungi were