<p>In this work, the fatigue crack growth rate (FCGR) on fillet welds and partial penetration welds was measured and examined. The special feature of the studied propagation is the unusual loading mode of such joints: bending loading from the root to face of the weld; such loading mode is very severe in fillet welds and partial penetration welds where the un-welded portion of the joints acts as a natural notch. Furthermore, apart from the behavior of the joints with a crack, the fatigue resistance was measured and the FAT was determined on different welds characterized by different welding penetration and thickness: The crack initiation fatigue resistance and the fatigue life to rupture were determined and compared. The path followed by the cracks during the tests revealed some unexpected features linked to the relation between throat thickness and the thickness of the membrane. The obtained data are a precious starting point to better investigate the behavior of such widely diffused joints under a loading mode not often considered on metallic structures but still present in a lot of cases. Albeit typically used for static loads, the studied joints can be submitted to cyclic loads during service for several reasons which are not predicted during design. Therefore, the assessment of the FAT and of the FCGRs will help to know what the real fatigue behavior of such joints is. In this way, the design of a structure will get benefits from a finer evaluation of each weld detail.</p>