A superior combination of ultrahigh strength and good ductility was achieved in ZK60 Mg alloy sheet processed by equal Channel Angular Pressing (ECAP) and subsequent cold rolling. The cold rolling almost doubled the yield strength while retaining moderate ductility. The ultrahigh strength was attributed to the ultrafine-grained structure with high density of dislocations. Nano-spaced parallel deformation strips were also observed and contributed to strength and strain hardening. The fine structure and non-basal texture of the rolled sheet rendered good ductility.