The deck receives a lateral external force as well as an in-plane force in relation to the longitudinal strength and the transverse strength, same as the shell and the bulkhead. Tensile and compressive stresses occur longitudinally on the upper deck due to the bending of the hull girder. For cargo ships and container ships, tensile and compressive stresses also occur transversely on the cross deck between the hatch openings. Decks and inner bottom plating are often under concentrated or locally distributed loads from various cargo and equipment such as vehicles, forklift trucks or steel coils. This chapter describes several design issues on deck structures, including stress concentration at hatch corners, strength evaluation for steel coils and wheel loads, and so on.