Base-labile 6-chloro-2',3',5'-tri-O-acetylpurine riboside (1c) and 2-amino-6-chloro-2',3',5'-tri-O-acetylpurine riboside (1d) were fully deacetylated through Candida antarctica B lipase hydrolysis, affording respectively 6-chloropurine riboside (2c) and 2-amino-6-chloro-purine riboside (2d). Quantitative results were found at pH 7 and 60 degreesC in 24 h for 1c and 72 h for 1d. This mild and simple enzymatic technique represents a convenient procedure for the removal of acetyl groups from such base labile halogenated nucleosides.