This study was conducted to assess the efficacy of aminolevulinic acid-based photodynamic treatment for residual or recurrent basal cell carcinomas after radiotherapy. Photodynamic therapy with either topical 5-aminolevulinic acid 20% and dimethylsulfoxide 99% pretreatment or topical methylester aminolevulinic acid 20% w/w in cream and subsequent light illumination of 50-200 J/cm2 was performed after an initial skin shaving procedure in 20 patients with 22 residual or recurrent basal cell carcinomas. Three lesions were treated once, while twelve, three, one and two lesions received two, three, four and five treatment sessions respectively. At examination, 6-40 months (mean 22 months) after the last treatment, 18 lesions were in complete remission. All lesions were considered excellent or good with regard to cosmetic outcome. Three lesions responded only partially to photodynamic therapy and a fourth lesion recurred 21 months after photodynamic treatment. Two of these four lesions were confirmed as the morpheaform type of basal cell carcinoma.