We evaluated the photoprotectioe efficacy of a broad-spectrum sunscreen containing a UVA screen (butyl methoxydibenzoyhnethane) and a UVB screen (octyl dimethyl p-aminobenzoic acid) in patients with hereditary polymorphic light eruption. At least 18 of the 30 patients who enrolled in the study were sensitive to sunlight through window glass, an indication of UVA sensitivity. Of the 21 patients who completed the clinical trial, the physician's evaluation was that 18 (86%) obtained good to excellent results. Self-evaluation by the patients revealed that 16 (76%) noted more photoprotection than from previous treatments.