BACKGROUNDPhotodynamic therapy (PDT) is an effective modality for the treatment of actinic keratoses (AKs). The use of methyl aminolevulinate with daylight PDT (D-PDT) has quickly gained popularity internationally because of its tolerability and high levels of safety and efficacy. However, there is a paucity of studies on the use of D-PDT with 5-Aminolevulinic acid (ALA).OBJECTIVETo study the safety and efficacy of D-PDT in treating AKs on the face and scalp using ALA.MATERIALS AND METHODSThirty patients were recruited for this prospective, uncontrolled study. Patients were treated with topical ALA on either the scalp or face, incubated for 30 minutes, and then sat at home in a shady area for 2 hours. Weather conditions, lux measurements, and AK counts at 3 and 6 months were measured.RESULTSDaylight PDT led to a median of 75% reduction in AK count at 6 months, with no significant adverse effects. Ninety-six percentage of patients were either moderately or very satisfied with the treatment, and the median peak pain score during treatment was 1. There was no correlation between weather or average lux received during treatment and 6-month outcomes.CONCLUSIONDaylight PDT with ALA is a safe and effective treatment modality for AKs on the head.