Complex aphthosis, the occurrence of recurrent oral and genital aphthous ulceration without manifestations of systemic disease, is relatively uncommon and of unknown aetiology. We describe a case of complex aphthosis which began within weeks of stopping smoking. After failing to respond to conventional agents, the patient was successfully treated with nicotine lozenges. Recurrent aphthous stomatitis (RAS) is known to be less common in smokers and there have been previous reports of nicotine being used as successful treatments for RAS and Behçet's disease. We discuss the mechanisms of action of nicotine whereby nicotine could influence the natural history of aphthous ulceration. We recommend considering its use when conventional management has failed, particularly in ex-smokers.