Aliphatic-aromatic copolyesters, synthesized by incorporating 10 mole % of 2,2 bis(4-hydroxy phenyl)propane, 4-4' dihydroxydiphenyl sulphone, hydroquinone, and resorcinol comonomers as a third component, were spun into fibers by the melt- spinning technique. The effect of various bisphenols on structure and mechanical properties of copolyester fibers was investigated. In spite of the introduction of unsymmetrical bisphenols, an increase in crystallinity and orientation was observed. There was a drop in the tensile properties of these copolyesters as compared to PET, which may be attributed to their low molecular weight and the total cohesive energy density. An increase in flame retardancy was also observed in these copolyesters.