Three patients, women aged 69, 25 and 30 years, with refractory keratitis were found to have a rare infection with Acanthamoeba. All wore soft contact lenses. The frequency of Acanthamoeba keratitis increased in recent years. At present, an efficacious antiprotozoal therapy is available, for instance in the form of polyhexamethylene biguanide and propamidine. In cases of refractory keratitis, the possibility of an Acanthamoeba infection should be taken into account.