Chronic recurrent aphthous stomatitis is one of the most frequent oral mucosal lesions which is characterized by the recurrent formation of aphthae and by the long clinical course with periodical presentation of signs. The exacerbation of recurrent stomatitis may be caused by the body state, by the seasonal character of allergic reactions, by changes of hormonal profile and by some other factors. It’s not rare that this condition is triggered by gastrointestinal diseases, helminthic invasions, severe quinsy or flu. Morphological lesions of chronic recurrent aphthous stomatitis represent aphthae localized in any area of the mucous membrane, but the most frequent location is the mucous membrane around the lips, cheeks, the lateral side of the tongue and the mucobuccal fold. The lesions affecting the mucous membrane are usually round in shape and covered by grayish-white fibrinous membrane. The treatment of chronic recurrent aphthous stomatitis, as the treatment of any lesion without clearly determined etiology and pathogenesis is not an easy task. General treatment and local treatment are chosen individually for each patient. General treatment includes a rigid diet excluding possible allergens, spicy and salty food; administration of non-specific desensitization medication: histaglobin, pirogenal, prodigiosine and lysozymes; vitamin therapy with the administration of ascorbic acid, pyridoxine, riboflavin, folic acid and nicotinamide. If the ulcers are deep, it is indicated to administer prednisolone in a basic or alternative way. The aim of local treatment is to manage the painful sensations, to strengthen the local immunity, to fight the infectious flora and to heal the affected mucous membrane. Clinical immunological tests aimed at finding associated pathologies are very important in treatment and prevention of chronic recurrent aphthous stomatitis.