During the course of a detailed study of the composition and ecology of the Phalangid fauna of Michigan several specimens of what appears to be an undescribed species of Leiobunum were collected from two sites in the southern half of the Lower Peninsula of Michigan; namely, Eaton County on July 20, 1957 and July 24, 1959 and Huron County on July 27, 1957. All specimens taken were immatures; however, several males and females were reared to maturity from the 1959 collection and one male is here described.