A prospective study was undertaken to evaluate the efficacy of 3 mm margins of resection with surgical excision of squamous cell carcinoma of the lower lip (SCCLL) in its early stages whereby the margins were checked with the systematic use of frozen-section examination. During the period of 1991-1998, 72 consecutive patients with a primary stage I/II SCCLL underwent surgical excision as the initial treatment. There were 58 males (81%) and 14 females (19%) with a median age of 66.8 years (range 37-91 years). The majority of cases (94.4%) were stage I tumours. Treatment consisted of a full-thickness excision including a 3 mm margin of clinically uninvolved tissue. Intraoperative frozen-section analysis of the margins of the excised specimen was used to confirm tumour-free margins. Clinically determined margins were tumour-free in 89.9% on initial excision. The false-positive rate associated with frozen-section analysis was 1.4%. The minimum follow-up period for all patients was 2 years (median 5.1 years, range 2-9 years). Local recurrence was found in two patients (2.8%). A 3 mm margin with excision of early SCCLL seems to be appropriate, if the margins are controlled by systematic use of frozen-section analysis.