Epiphytic bacteria are subjected to very stressful environments, including UV radiation. Bacterial assemblages on Zea mays (maize) leaves exposure were examined with and without UV-B radiation. Culture-independent molecular techniques were utilized for bacterial identification, diversity analysis and selection of putative UV exposure marker sequences. Few sequences corresponded to previously characterized phyllosphere bacteria. There was a strong tendency toward increased 16S rDNA sequence diversity in UV samples. Overall community structure was assessed using denaturing gel gradient electrophoresis; significant alterations in community structure were found in comparisons of phyllosphere bacterial samples from control and solar UV-B exposed plants.