Synthetic dyes had become more available than natural dyes because of their lower prices and wider ranges of bright shades with considerably improved color fastness properties. Recentty, concern for the environment has created an increasing demand for natural dyes which are more friendly to the environment than synthetic dyes. This investigation alms to study the effect of dyeing cotton fabrics with natural dye (henna) and synthetic dye (remazol blue) on some mechanical properties and stability to Gght exposure. The undyed and cotton fabrics dyed were tested for tenacity (N), elongation %, breaking work (Nm). Shrinkage and crease recovery angle were also tested. The stability to light exposure after 100 hr were examined by investigation of macrostructure (using scanning electron microscope) and reflection spectra. The results proved that the cotton samples dyed with henna have higher mechanical properties, higher shrinkage % and higher recovery angle. Moreover, fabrics dyed with henna showed lower degree of degradation when exposed to the artificial daylight for 100 hr, while the remazole blue showed the highest degradation.