The aim of this study was to document and compare the corticolous lichen species diversity present on barks of trees at four study sites in urban and suburban environments in New Amsterdam, Guyana. A 50m by 20m plot was demarcated within each of the four sites. Healthy mature trees within the each were sampled to determine species richness, evenness and diversity of corticolous lichens communities. Forty-one healthy individual trees from five species were sampled using (10cm by 50cm) ladder quadrats on the tree trunk (N, S, E, W) at 150cm height. A total of 14978 individual lichens were identified from 10 families, 13 genera and 18 species. Shannon Diversity Index and Simpson’s Diversity Index, Pielou’s Index, Menhinick’s Index and Whittaker’s diversity index were calculated and used to compare the lichen diversity. The results showed that species richness, species evenness and diversity was higher at the urban study sites than at the suburban sites. Index terms: Corticolous lichens, diversity, urban, suburban, Guyana.