It is shown that magnetohydrodynamic (MHD) effects present not only an efficiency but also a feasibility issue for self-cooled liquid-metal blankets of magnetically confined fusion reactors, especially tokamaks. For this reason, MHD considerations are the main driver in the development of the design of such blankets. This paper, intended for the designer, presents in a unified way these considerations, as well as effective strategies to deal with adverse MHD effects.