Background: Basal cell carcinoma (BCC) is the most common form of cancer among Caucasians and its incidence continues to rise. Surgical excision (SE) is considered standard treatment, though randomised trials with long-term follow-up are rare. We now report the long-term results of a randomised trial comparing surgical excision with Mohs' micrographic surgery (MMS) for facial BCC. Methods: 408 facial, high risk (diameter at least 1 cm, H-zone location or aggressive histological subtype) primary BCCs (pBCCs) and 204 facial recurrent BCCs (rBCCs) were randomly allocated to treatment with either SE or MMS between 5th October 1999 and 27th February 2002. The primary outcome was recurrence of carcinoma. A modified intention to treat analysis was performed. Findings: For primary BCC, the 10-year cumulative probabilities of recurrence were 4.4% after MMS and 12.2% after SE (Log-rank test chi(2) 2.704, p = 0.100). For recurrent BCC, cumulative 10-year recurrence probabilities were 3.9% and 13.5% for MMS and SE, respectively (Log-rank chi(2) 5.166, p = 0.023). A substantial proportion of recurrences occurred after more than 5 years post-treatment: 56% for pBCC and 14% for rBCC. Interpretation: Fewer recurrences occurred after treatment of high risk facial BCC with MMS compared to treatment with SE. The proportion of recurrences occurring more than 5 years post-treatment was especially high for pBCC, stressing the need for long-term follow-up in patients with high risk facial pBCC. (C) 2014 Elsevier Ltd. All rights reserved.