A study of the tensile behaviour of non woven geotextiles of different structure and polymer types has been reported. The mechanical properties of the constituent fibres of these fabrics have been evaluated on the Instron tensile tester and the fabric structure has been studied using a projection microscope. Fibre network theory has been applied to theoretically predict the stress-strain behaviour of these fabrics. Tensile tests on wide width specimen have been conducted in order to evaluate the theory. In the case of thennally bonded spunlaid fabrics which have fairly strong bonds due to fusion of fibres at intersections, the theory leads to fairly good approximation. In case of needle-punched spunlaid fabrics, although there will be large deformation due to slippage at the bonding points and change in fibre orientation at the initial stage, slippage at the fibre ends which occurs due to finite length of staple fibres is not going to take place. In order to see the applicability of fibre network theory and the extent to which it can be used in the absence of a more rigorous theory, this theory has also been applied in-case of needle-punched spunlaid non woven fabrics.