The contents of this paper are concerned with a comparison of theoretical and full-scale responses for the 26, 800 dwt container ship “Pacific Arrow” when serving in the North Pacific Ocean. The measurements were carried out on five voyages of the ship, and the test data were obtained on the main-hull stresses due to waves as well as vertical accelerations of ship's motion. In addition to these, the theoretical analysis was performed on the statistically estimated long-term stresses in the longitudinal strength members of the ship by means of the total system analysis computer programme developed by Nippon Kaiji Kyokai. Comparisons between the theoretical predictions and the processed test data by the measurements indicate good agreement for the longitudinal stresses of the main-hull girder of the ship.