Degradation defects induced by electron-beam bombardment in Zn1-xCdxSe/ZnSe (001) graded-index separate-confinement blue-green laser structures have been characterized by transmission electron microscopy. Most defects appear as tree-like arrangements of small extrinsic and intrinsic dislocation loops opening in +/-[100] or +/-[010] directions and are located within the quantum well or at its boundaries. The Burgers vectors of the loops were identified as b = 1/2[01(1) over bar] and b = 1/2[10(1) over bar] for defects opening in the +/-[100] and +/-[010] directions respectively.