BACKGROUND: Lentigo maligna (LM) and lentigo maligna melanoma (LMM) are the most common melanocytic neoplasms on sun-exposed skin of elderly patients. OBJECTIVES: To perform a retrospective study of 150 patients with LM and LMM treated with radiotherapy using Grenz or soft X-rays. METHODS: The information recorded and analysed included gender, age, diagnosis, size of the lesion, localization, X-ray treatment, recurrence rate, other skin malignancies and non-dermatological neoplasms. RESULTS: The 150 patients comprised 78 women and 72 men (mean age 70 years). Ninety-three patients had LM, 54 had LMM and three had both neoplasms. Ninety per cent of lesions were located on the face. Treatment was with Grenz rays in 96 patients with LM and 11 with LMM (70%) and with soft X-rays in 46 patients with LMM (30%). Three patients were treated using both modalities. One hundred and one patients were followed up for at least 2 years after radiotherapy (mean 8 years). The mean time to recurrence was 45.6 months, and the recurrence rate was 7% (seven of 101). Other skin malignancies were observed in 65 of 150 patients, including basal cell carcinoma in 23 (35%) and actinic keratosis in 20 (31%). Four patients developed internal cancers. CONCLUSIONS: The study showed that radiotherapy of LM and LMM was curative. In particular, radiotherapy proved to be an excellent treatment for elderly patients. Owing to the high incidence of other skin cancers, LM patients need careful follow-up.