Biomonitoring properties of some foliose and crustose lichen species were studied in a polluted area of Giresun city, in the northern part of Turkey caused by high traffic density. Heavy metal concentrations were usually ranked in the order of Fe > Zn > Mn > Cu > Pb in the studied lichen species. Fruticose Cladonia species were significantly different from foliose species in terms of heavy metal concentrations except for Pb and Zn. Interspecific differences with respect to heavy metals were observed between the studied species except for Pb. According to Principal Component Analysis (PCA) the main loading factors in the first axis were Fe and Mn in the positive zone. However, Zn followed an opposite behaviour in relation to other heavy metals and occured in the negative zone.