The sharkskin defect appearing during the capillary extrusion of three low-density polyethylene resins with different molecular structures has been characterized. Using complementary techniques, profilometry, optical microscopy, and observation of cross sections, the amplitude and the period of the defects have been measured accurately. The influence of flow rate, temperature, and die geometry has been quantified. The specific behavior of the orifice die has been put in evidence. It shows that, if the role played by the stress field is evident, the wall shear stress is not the unique determinant of the sharkskin process. The influences of molecular structure and elongational behavior on sharkskin are discussed. It appears that resins exhibiting long chain branching and strain hardening are less sensitive to sharkskin.