Characterization of cotton fibre is complex due to the effects of growing and harvesting conditions on the cotton plant. Understanding the structure of a cotton fibre is very important in order to elucidate the influence of many parameters on its mechanical properties. In this chapter, after a brief overview of the cotton fibre structure and the physical properties of fineness, maturity, micronaire and length, the tensile properties (for single and bundle fibres) and the relationship between them is examined using results from our current research. Using parameters defined by analogical models, the effect of stress on fibre creep and the fibre’s visco-elastic properties are examined.