Abstract: Method for treating a proliferative skin disorder, such as psoriasis, in a human patient having affected and non-affected areas of skin. The method comprises the steps of: (1) topically applying a sunscreen providing photo-protection to the affected and non-affected areas of skin; (2) waiting for a time period sufficient for the skin of the affected areas to be substantially sloughed off; and, (3) exposing the affected and non-affected areas of skin of the patient to a selected level of optical radiation. The level of radiation is chosen to be sufficient to treat the affected areas of skin and insufficient to cause significant damage to the non-affected areas of skin. The method enhances effectiveness and safety of treatment by providing preferential photo-protection to the non-affected skin areas, and may be used for phototherapy, photochemotherapy, or photodynamic therapy.