Dyeing and fastness properties of alkali-clearable disperse dyes of diester type, which were synthesized using diazo components derived from terephthalic acid, have been studied. They had good build-up properties and showed high exhaustion on regular polyester fiber. Washing and abrasion fastnesses of dyed polyester fabrics were excellent due to the solubility of the dyes in alkaline solution. Increase in molecular weight by introducing bulky sub-stituents to the dye improved sublimation fastness, while the addition of cyano group improved light fastness as expected. Fine denier polyester fabric dyed with the new disperse dye also exhibited excellent washing fastness. The newly synthesized dye barely stained cotton fiber, and gave good washing fastness of polyester/cotton blended fabric dyed by a one-bath dyeing method.