This paper deals with the method and results of a full scale statical test on the transverse strength of a 180, 000 DWT oil tanker, in which some new design features are seen in the structural arrangement of its cargo oil tank construction, such as arched-type bottom transverses in center tank of centerline girderless system, transverse ring constructions with no struts in wing tank adjacent to the watertight bulkhead, large round bracket connection of bottom centerline longitudinal to the lowest horizontal girder attached to the transverse bulkheads, etc.. An extensive measurement is carried out on the stress distributions in structural components of the transverse strength members at 221 measuring points, as well as on the vertical deflections of hull girder and wing tank deformations of the ship. Accuracy of the test results is checked by evaluating their standard deviations through the least square method, and is assured that more than 90% of the strain readings are of tolerance within ±1 kg/mm². Theoretical analysis is also made on the transverse strength calculations of the ship with use of computer programs for three-dimensional frame work analysis associated with the finite element method for plane structures. It is found from a comparison between the theoretical and the experimental results that the deformations and the stress distributions in tanker structures can generally be predicted by the above-mentioned computer programs within a satisfactory accuracy for practical design purpose.