The testing of knitting fabrics before being used in the garment industry is an issue of great importance to improve the quality of the final product. This research aims tostudy the effect of knitting variables, eg. Fabric structure, loop length, yarn count, and yarn material on thickness, bursting strength and air permeability of some weft knitted fabrics. For this purpose three knitted structures (single jersey, rib1×1, interlock 1×1) were knitted with two levels of loop lengths, two yarn counts, and two different yarn material ( cotton100%, cotton polyester 50/50)for each structure to produce twenty –four samples; eight samples for each structure. The findings of this study revealed that  thickness and bursting strength values for interlock fabrics is generally higher  than rib fabrics, and both of them are higher than single jersey fabrics,It was found that the fabrics with the same structure knitted with cotton-polyester yarns shows high bursting strength values more than the fabrics knitted with cotton yarns . It was also found that the fabrics with the same structure knitted using short loop length are thicker and gives higher fabric bursting strength values and air permeability of the fabric decreased remarkably. For the yarn count the fabrics knitted with finer yarn count are thinner, gives the lowest fabric bursting strength value while air permeability of the fabric increased. This research helpsgarments manufacturing to understand the nature of weft knitted fabrics and factors that are affected by these fabrics, which can be controlled to select a suitable raw material for the final product.