Ocean heat content is a major component of earth's energy budget. This paper presents estimates of the climatological annual cycle of upper (0--250 m layer) ocean heat content based on World Ocean Atlas 2001. The land-ocean ratio is responsible for the geographical distribution of the annual cycle of ocean heat content. Globally, the amplitude of annual harmonic of upper ocean heat content is 3.7 ¿ 1022 J for the World Ocean, 10.2 ¿ 1022J for the Southern Hemisphere, and 6.5 ¿ 1022J for the Northern Hemisphere.