The thermodynamic properties associated with the surface layer of a Heisenberg ferromagnet on the semi-infinite simple cubic lattice are examined systematically in the molecular-field approximation. The surface critical temperature and the critical exponents are determined for various ratios of the surface exchange constant Js=(1+ Delta )J to the bulk exchange constant J. It is found that the surface critical temperature Tcs is higher than the bulk transition temperature Tcb for 4 Delta >1. In this case the surface critical exponents are identical with the bulk exponents. On the other hand, for 4 Delta <1, it is found that the surface and the bulk phase transitions occur at the same temperature, but with different critical exponents.