Abstract. The growth of lampenflora detracts the natural beauty of cave walls, and threatens their archaeological value.

This is a real problem in Malaysian caves, therefore, an attempt should be made to eliminate these unwanted microorganisms. Ultraviolet light destroys harmful microbes such as bacteria, yeast. molds, viruses and algae, and ultraviolet radiation is less toxic to cave dwellers such as birds, reptiles and visitors. So ultraviolet radiation can be a way to control microorganisms or reduce their numbers. In this study. we studied the effect of ultraviolet radiation on microorganisms isolated from selected Malaysian caves to control and eliminate them AlterS minutes exposure, 254mm UV-C effectively eliminated colonies of Pseudomonas aerginosa and Stenotrophomonas sp. But P. guilliermondi and

R. dairenensis were eliminated to the zero after 30 mivutes of treatment, but C. Liquefaciens needed 60 minutes to be treated. Synechochococcus sp and Micractinium sp. fell to zero after exposure to 240 of UV-C