The monoclonal antibody Ki-1(CD30) was first described in 1982 and was reported to react selectively with Reed-Sternberg cells in Hodgkins disease, highly activated B and T cells and large cell lymphomas of both T-and B-cell origin. Lymphomatoid papulosis(LyP) is characterized by recurrent erythematous papules or nodules that undergo spontaneous healing with hyperpigmentation and scarring. Histologically, two major types of LyP can be distinguished: type A is characterized by the presence of variable numbers of Ki-1+ large, atypical lymphocytes with some Reed-Sternberg like cells and type B is characterized by Ki-1- atypical cerebriform mononuclear cells similar to those in mycosis fungoides. We report a case of Ki-1+ lymphomatoid papulosis which was histopathologically recognized as a type B lesion but represented a Ki-1 positive reaction, (Korean J Dermatol 1998;36(3): 540-544)