Background: oral ulceration is the earliest and commonest manifestation of Behcet's disease (BD). Minor aphthous like ulcers (<10 mm in diameter) are the most common type (85%); major or herpetiform ulcers are less frequent. It is occurred about in Egypt; 3.6/100,000 % and high recurrence rate with traditional treatment. Colchicine is the first line of treatment in mucocutaneous manifestation of BD through its anti-inflammatory effect. Tacrolimus oral gel is safe and effective in treating aphthous ulcers in many diseases. Objectives: to compare the clinical efficacy of topical tacrolimus versus oral colchicine upon disease activity, pain and ulcer severity in oral ulcer associated with BD. Study design: A randomized double -blinded trial.

Setting: Rheumatology clinic, Assiut University Hospital and Faculty of Dental Medicine, AlAzhar University, Assiut branch outpatient's clinic. Methods: 40 BD participants (> 3 months taken traditional treatment with persistent active oral ulceration). They have been equally randomized into either group I (Colchicine and topically applied Tacrolimus), or group II (Colchicine only). Measurements: Behcet's Disease Current Activity Form (BDCAF), Ulcer Severity Score (USS) and visual analog scale (VAS) pre-injection, then re-evaluated postinjection at four-time points (15 days, 1st, 2nd and 3rd months) and Determination of Natural Killer (NK) cells number in salival wash before treatment (at base line) and after the treatment (after 3 months)

Background: oral ulceration is the earliest and commonest manifestation of Behcet's disease (BD). Minor aphthous like ulcers (<10 mm in diameter) are the most common type (85%); major or herpetiform ulcers are less frequent. It is occurred about in Egypt; 3.6/100,000 % and high recurrence rate with traditional treatment. Colchicine is the first line of treatment in mucocutaneous manifestation of BD through its anti-inflammatory effect. Tacrolimus oral gel is safe and effective in treating aphthous ulcers in many diseases. Objectives: to compare the clinical efficacy of topical tacrolimus versus oral colchicine upon disease activity, pain and ulcer severity in oral ulcer associated with BD. Study design: A randomized double -blinded trial.

Setting: Rheumatology clinic, Assiut University Hospital and Faculty of Dental Medicine, AlAzhar University, Assiut branch outpatient's clinic. Methods: 40 BD participants (> 3 months taken traditional treatment with persistent active oral ulceration). They have been equally randomized into either group I (Colchicine and topically applied Tacrolimus), or group II (Colchicine only). Measurements: Behcet's Disease Current Activity Form (BDCAF), Ulcer Severity Score (USS) and visual analog scale (VAS) pre-injection, then re-evaluated postinjection at four-time points (15 days, 1st, 2nd and 3rd months) and Determination of Natural Killer (NK) cells number in salival wash before treatment (at base line) and after the treatment (after 3 months)

Inclusion Criteria:

• active oral ulcers for Behcet's Disease

Exclusion Criteria:

• patients who received biological therapy comorbid systemic diseases allergy to Tarcolimus drug.