The buccal nerve may be damaged during surgical procedures which require an incision along the external oblique ridge of the mandible and this study was undertaken to clarify its surgical anatomy. The course and relationships of the nerve were determined in 20 formalin-fixed cadaver specimens. The number of major branches of the nerve ranged from 4 to 8 and a mean of 3 branches was present as the nerve crossed the external oblique ridge. In 14 dissections the main trunk of the nerve crossed the external oblique ridge within 3 mm of the deepest concavity, but in the other 6 it was 7-12 mm below this point. We conclude that incisions even 12 mm below the deepest concavity in the external oblique ridge could result in buccal nerve damage.