In this paper, we completely determine the commutativity of two Toeplitz operators on the harmonic Bergman space with integrable quasihomogeneous symbols, one of which is of the form e ikθ r m . As an application, the problem of when their product is again a Toeplitz operator is solved. In particular, Toeplitz operators with bounded symbols on the harmonic Bergman space commute with T e ikθ r m only in trivial cases, which appears quite different from results on analytic Bergman space inČučković and Rao ['Mellin transform, monomial symbols, and commuting Toeplitz operators', J. Funct. Anal. 154 (1998), 195-214].2010 Mathematics subject classification: primary 47B35.