Propolis is more and more popular with the trend of ”come back to nature”. It is used in bio-cosmetics and self treatment of various diseases by it's pharmacological properties of antiseptic, antimycotic, anti-inflammatory, astringent and anesthetic activities. The expression of propolis allergy in oral cavity includes: erosive ulceration and desquamation of oral mucosa, eczematous lesions of periodontal tissue, stomatitis and contact dermatitis-like lesions in skin .The differential diagnosis should include erythema multiforme and acute necrotizing ulcerative gingivitis, Detailed history taking and analysis combined with patch skin test is important foroia1nolis. The treatment of propolis allergy includes: desensitized treatment, symptomatic treatment and anti-inflammatory treatment. This article describes a patient who had acute oral mucositis with ulceration and discomfort in periodontal tissues as a result of propolis allergy.