Abstract: Comet assay or single-cell gel electrophoresis is now widely used to detect DNA damage in cultured animal cells, but only a few reports describe the application of comet assay in plant cells. Here, the accepted animal cell protocol was modified to adapt it to plant cells and the sensitivity to UV-B induced DNA damage was investigated in young and mature leaves of Murraya panicuata. Both UV-A and UV-B irradiation induced DNA damage in mesophylls. The level of DNA damage was much higher in younger than mature leaves, which indicates that young leaves are more sensitive to UV-B radiation than mature leaves.