In an effort to uncover the reproduction of Korean brook perch Coreoperca herzi testis anatomy and sperm morphology were studied. Fish samples were collected in the sooypcheon river from May to October 2001. White-colored testes have wedgeshaped external morphology, and developed symmetrically in the dorsal cavity of the trunk. Isogenetic germ cells developed in the cyst located in seminiferous lobule. Each lobule showed significant asynchrony in the spermatogenic stage of the cyst. Sperm was 43 ㎛ in length. The round head was 2.2 ㎛ long. The middle piece developed beneath the head was 0.5 ㎛ long. Tail was 40 ㎛ in length. Coomassie brilliant blue(CBB) gave rise the intense staining in the apex of sperm head and middle piece, suggesting the possible development of acrosome.