The mechanical behavior of the Mg65Cu25Gd 10 bulk metallic glasses (BMGs) in term of compression testing is reported in this study. Room-temperature compression tests are conducted on specimens with various height to diameter ratios (h/d) from 2 : 1, 1 : 1, 1 : 2, to 1 : 4. The failure strength, deformation strain, and the fracture surface morphologies are seen to vary systematically in accordance with the specimen h/d ratio. For specimens with h/d of 2 : 1 or 1 : 1, the compression response is similar to those in most reports. In contrast, for specimens with lower h/d ratios, especially at h/d = 1 : 4 (or 0.25), the shear band propagation appears to be constrained, resulting in the enhanced ductility. It suggests that different deformation mechanisms are operative for specimens with different h/d ratios. The possible deformation mechanisms in specimens of different geometries are discussed.