Background : Beckers nevus is a benign lesion that may be congental or acquired, macular or papular, hairless or hypertrichotie. Objective : Our pcrpose was to describe the clinical findings of Eeckers nevus and to establish a method for the histologic diagnosis of Beckers nevus. Methods : We reviewed PF skin biopsies and their clinical finding from 28 patients with Beckers nevus during a 10 year period from January 1981 to January 1991. Results : The results were summarized as follows. A Clinical characteristics 1. Sex distribution showed of male predominence with male female a ratio of 1.5:1. Age of onset was predominent in less that 5 years old and puberty. 2. The lesions were located on the trunk(24 cases), head & neck(8 cases), extremities(6 cases), and were repsilateral in 26 cases, bilateral in 2 cases. 3. The lesions were accompanied by hair in 17 cases(61%). The shaies of the lesions were reticulated (75 %), patch(18%), mottled(7%). 4. Hairs were distributed as follows : abdomen(100%), scapula(100 %), extremities (83%), cheek(80 %), neck(67 %), chest(40%). All lesions of the face had follicular papules. 5. Associated skin diseases were : smooth muscle hamartoma(3 cases), striae distensa(2 cases), steroid acne(2 cases), pigmented nevus(2 cases), and verruca plana(1 case). B. Histopathologic characteristics 1. The lesions were accompanied with plugs in 21 cases, which were follicular, acrosyringeal, epidermal. 2. Elongation of the rete ridge and hyperpigmented basal cells were observed in the epidermis in all cases. 3. The shape of the rete ridge in Beckers nevus has its characteristic appearance, which is single, bridging and reticulated. Single, bridging and reticulated shapes cexisted in 17 cases(61%). 4. Inflammatiry cell infiltrations were present in all of the upper drmis, in which melanophages(21 %), hair follicles(89%) and smooth muscle hamartoma(3cases) w ere observed Conclusion : These findings indicated that the shape of the rete ridge in Beckers nevus has its characteristic appesrance and can be useful for the diagnosis of Beckers nevus. (Kor J Dermatol laa3;31(4):539-547)