: Corrugated core sandwich panels are comprised of a relatively thick and low-density corrugated core sheet. The core is sandwiched between two usually thin and stiff skins. The use of corrugated core sandwich panel is very prevalent in mechanical and aerospace structures. Composite forms of these structures suffer from delamination phenomenon due to the rather weak adhesion between the core and the skins. In this thesis, using recent advances in the field of 3-D weft knitting technology, the reinforcements of integrated corrugated core sandwich panel with rectangular, hat-type or trapezoid and triangular core geometries were knitted. In order to be able to compare composite samples of similar weights, the 3-D reinforcement with different core geometries were prepared using glass fiber yarns of different yarn counts during knitting operation. VARTM composite making method was used to fabricate composite samples using epoxy resin. This research also examines the effect of 3-D reinforcement and the structural integrity on mechanical properties of corrugated core sandwich panels. This was achieved using 2-D weft knitted fabrics which were laminated in such a manner that the non-integrated structure with rectangular core was fabricated with up most similarities to the integrated structure. In non-integrated structures, the resin bonds the core to the skins while in the integrated composites, in addition to the resin, yarns also participate in bonding of the constituent layers to each other. Flexural stiffness, transverse shear rigidity and core shear modulus of the composites samples were determined using 3-point and 4-point bending tests. The results of flexural loading pointed to better performance of the triangular structure in the direction of corrugation. The triangular structure was found to have higher transverse shear rigidity and core shear modulus in the direction of corrugation than the hat-type or rectangular structures. It was also found that the hat-type structure has higher transverse shear rigidity and core shear modulus in the transverse direction of corrugation than the other structures. It was found that beams made of the integrated structure with rectangular core perform better in the transverse direction of corrugation. This phenomenon is important due to the fact that corrugated core sandwich panel are mostly used in the transverse direction of corrugation. The results showed that the integrated structure has greater flexural stiffness in the transverse direction of corrugation than the non-integrated structure. However the integrated structure was found to have low performance in the direction of corrugation than the non-integrated structure. Experimental modal analysis revealed that the effect of core geometry and structural integrity of corrugated core sandwich panel composites on the natural frequency is significant. It was found that changes in the core wall geometry from 41? to 90?, reduces the natural frequency. Additionally it was found that the natural frequency of the integrated structures is significantly higher than that of the non-integrated structures. This phenomenon emphasizes that the natural frequency can be changed without the need to alter mass or dimensions of the structure using 3-D weft knitting technology. The finite element results of the elastic constants and natural frequency of structures, both in the direction of corrugation and in the transverse direction of corrugation were found to be highly compatible with the experimental results.