Subdecadal changes in Earth's rotation rate, and hence in the Length of day (LOD), are largely controlled by variations in atmospheric angular momentum. Results from two oceanic general circulation models (OGCMs), forced by observed wind stress and heat flux for the years 1992 through 1994 show that ocean current and mass distribution changes also induce detectable LOD variations. The close similarity of axial oceanic angular momentum (OAM) results from two independent OGCMs, and their coherence with LOD, demonstrate that global ocean models can successfully capture the large-scale circulation changes that drive OAM variability on seasonal and shorter time scales.