Activity concentrations of gross-beta, naturally occurring Ra-226, Th-232, Pb-210, Be-7 and anthropogenic Cs-137 in epiphytic lichens collected from Uludag Mountain are presented and discussed with the aim of evaluating potential usability of lichens as a biomonitor. The activity concentrations of gross-beta, Cs-137, K-40, Ra-226, Th-232, Pb-210 and Be-7 in the lichen samples were found to be in the range of 177-707, 4.05-94.26, 86-211, below detection limit (BDL)-19.2, BDL-14.0, 229-872, and 72.1-220.7 Bq kg(-1) in dry weight, respectively. Cs-137 content in collected epiphytic lichens was in descending order: Parmelia sulcata > Lobaria pulmonaria > Pseudevernia furfuracea > Usnea filipendula. The best biomonitor for Cs-137 among the lichen species used in this study was determined as Parmelia sulcata. Pearson's correlation coefficient was calculated between Cs-137 and K-40 activity concentrations using a statistical package program (SPSS ver. 17.0) and a negative correlation value (R = -0,323, p = 0,222) was obtained. The highest Ra-226 and Th-232 activity concentrations were found in Bogazova YaylasA +/- which has a geological structure including granitic rocks. It was found that Cs-137 and Be-7 activity concentrations in species demonstrated an inverse behaviour. The effect of mean annual precipitation and temperature on Be-7 activity concentration was determined using multi regression analysis. Also, correlations between the Cs-137 and Be-7, and K-40 and Be-7 were investigated.