The methyl ester of ibuprofen is the most common starting material for the enzymatic resolution process based on selective hydrolyses of racemic mictures of ibuprofen esters. Addition of the methyl ester of racemic ibuprofen to growing cultures of Pseudomonas, Mucor, Arthrobacter or Bacillus species produced (S)-(+)-ibuprofen in 74-98% ee. Lipase from Candida rugosa hydrolyses racemic ibuprofen methyl ester to give 95% ee (S)-(+)-ibuprofen.