We develop a new model bomb-3H budget for the North Atlantic between 1950 and 1986. The model, which calculates the atmospheric and continental 3H delivery as well as the advective 3H transports from the South Atlantic and Arctic, agrees within about 10% with the 3H inventories computed from the 1972 GEOSECS and the 1981--1983 Transient Tracers in the Ocean (TTO) observations. The decay-corrected 3H inventory for the North Atlantic increased by about 43% between the GEOSECS and TTO programs (1972 and 1981), and the inflow of high 3H polar water from the Arctic into the North Atlantic is found to be crucial for correctly simulating this increase. Key aspects of the model that differ from previous studies include the treatment of vapor/rain isotopic equilibrium, the continental vapor flux, and the downward flux of water vapor into the ocean. The sensitivity of the atmospheric 3H delivery to model parameters and to seasonal and interannual variability are explored. ¿ American Geophysical Union 1993