Monitoring of lichens as bioindicators of air pollution has been conducted in Sokółka. On the basis of the occurrence of indicator epiphytic and epilithic lichen species, the scale of lichen sensitivity for the city has been developed and lichen zones have been designated. The zone pattern was not of insular character, and as a result there was no “total lichen desert”. The distribution of lichen zones reflects the intensity of anthropogenic pressure within the town. The least favourable conditions for lichen growth have been recorded in the town centre, while the green areas have shown the most beneficial impact on the lichen test sites