The invention relates to a method for purifying a glycoprotein, preferably FSH or a FSH mutant comprising the steps of subjecting a liquid containing said FSH or a FSH mutant to: (1) a dye affinity chromatography; (2) a weak anion exchange chromatography (3) a hydrophobic interaction chromatography; and (4) a strong anion exchange chromatography ; which may be carried out in any order.
