Biological quality of lettuce plants Bora cv. was estimated on the basis of nitrates and heavy metals contents. The lettuce plants were cultivated on three different hortisols, which contained different quantities of heavy metals, such as Pb, Ni, Cd, Mn, Cu and Zn; the pH values of the hortisols were also different (pH 4.4; 5.3; 7.1). Plant cultivation was localized near the „Bolmar” industry facility in Zamość region. The biological quality of lettuce plants, grown on acid hortisols (pH 4.4 and pH 5.3) was decreased. These hortisols contained excessive levels of heavy metals. The plant yield was low and the plants contained nitrates and heavy metals (Ni, Cd, Pb, Mn) in the amounts exceeding limits permissible for human consumption.