Abstract: Introduction: Mucous membrane manifestations of Behcet's Disease (BD) are the most important and frequent lesions of the disease. The classic lesions are well known. Other forms exist that are not given usually enough attention. Mucous Membrane Manifestations: The classical lesions are the oral and the genital aphthosis. 0ther forms are: 1- Rare forms of oral aphthosis: a/- Punctiform aphthous lesions: They are small and difficult to see. b/- The miliaria aphthosis: It resembles the punctiform aphthosis, but the elements are numerous, more than 50. c/- The herpetiform lesions are grouped together like herpes simplex. They may be mistaken with miliaria aphthosis. d/- Striated pattern lesion: a rare and curious form resembling lichen planus. It is painful and has a well-limited margin. 2- Anal aphthosis: It is rare. It is external and close to the sphincter. It is like the genital aphthosis. 3- Conjunctival aphthosis: It is rare, ephemera, and usually missed due to its small size. 4- Ulceration and erosions: They are rare. The fissural form was seen only on the tongue; Other forms included punctuated form, slashed form, open book like superficial ulceration and giant ulceration. The superficial and confluent forms are difficult to differentiate from the early stage of pemphigus vulgaris Without histological proof. 6- Purpura and hemorrhagic lesions: They are usually small and round, but they can also he widespread like a superficial hemorrhage. 7- Erythema: They usually surround aphthous lesions, but they- can be isolated. SKIN MANIFESTATIONS: Apart the classical forms, the following manifestations can be seen. 1- Small round ervthemato-edematous lesions: It is characterized by a wheal on the skin. It is slightly painful and is often seen on the lower limbs. 2- Cutaneous aphthosis: They are round; large (20 to 30 mm), multiple, and punched out ulceration with yellowish necrotic base. They leave a scar after I healing. 3- Small nodules: They are indurated dermic nodules, more palpable than visibIe. They are small and painful. They are mainly seen on the limbs and fingers. 4- Behcet's Cellulitis: It is painful large round erythemato-edematous lesion. It is to be differentiated from Sweet syndrome. 5- Rare lesions: a/- Livedo Racemosa on the lower limbs. b/- Spontaneous Round Ecchymosis on the I lower limbs. c/- Palpable Purpura. d/- Recurrent Erythema Multiform. e/- Pyoderma Gangrenosum like lesions. 6- Subcutaneous Lesions: Apart the classic erythema nodosum, the following were seen. a/- Multiple small nodules. b/ Bazin’s Erythema Induratum like lesion: Recurrent large subcutaneous, red mauve and indurated lesions. c/- Weber Christian like panniculitis: Multiple and recurrent episode is of fever with few subcutaneous nodes. The nodes became liquefied followed by a fistula draining a sterile liquid and left a localized skin atrophy with a round depressed region.