This study is a multicenter study investigating the clinical efficacy of repetitive daylight-PDT with MAL (Methylaminolevulinate) compared to cryosurgery in regard to prophylaxis and treatment of AKs (actinic keratoses) in the face. Patients will be randomly allocated to treatment groups. 5 PDT (photodynamic therapy) treatment sessions (visits 1-5) will be performed within 18 months. In the control group, cryosurgery will be performed at visit 1, and in case of non-cleared or newly occurred AKs at visits 2-5.