This paper reports a theory for the magnetostatic-surface-wave (MSSW) and magnetostatic-forward-volume-wave (MSFVW) reflection characteristics of a single shallow groove for the general case of oblique incidence. While a Brewster angle is nonexistent for MSFVW reflection, it is found to exist for MSSW's in certain frequency regions. The MSFVW reflectivity of a groove increases monotonically with the angle of incidence θ i A significant mode conversion of the lowest-order incident MSFVW into higher-order generated MSFVW's is found to exist. The reflection of a MSSW localized at the same surface as the groove is determined to be significantly weaker than that of a MSSW localized at the opposite YIG surface from the groove.