The authors present the results of a retrospective study of 495 non melanoma skin cancer (NMSC) lesions of the face treated with Mohs micrographic surgery (MMS) over a six year period. The size of the lesion was calculated as the difference between the lesion size and the final defect after surgical excision. Basal cell carcinoma and squamous cell carcinoma were independently analysed and each lesion was categorised as high or low-risk depending on size (bigger or equal / smaller than 2cm), histology (subtype, differentiation, perineural involvement) and recurrence status (primary or recurrent tumour). Results of the study showed that in order to safely remove low-risk NMSC lesions, a 5mm safe margin is needed if we want recurrence rate to be under 5%. In case of high-risk lesions this safe margin rises to 8mm for basal cell carcinoma and 13.25mm for squamous cell carcinoma. MMS is highly recommended in high-risk lesions and in cases where tissue resection should be keep to a minimum such as the medial canthus. The paper provides valuable data on oncologic surgical margins to the facial plastic surgeon. Classic 3mm safe margin increases to 5mm for low-risk lesions; the role of MMS is clearly defined and some surprising information about the smaller margins found in lesions inside the H-zone is presented. This is a highly recommended paper for surgeons who regularly deal with cutaneous malignancies.