Polyesters (PES) fibers are one of the most important polymers for textile industry due to their large production amounts. Poly (butylene terephthalat) (PBT) fibers are important aromatic polyesters known as their good elasticity and easy dyeing properties. PBT is manufactured by again polycondensation reaction with BDO (1,4-butanediol) and TPA or DMT, can be easily dyed at low temperatures with disperse dyes without carrier and is known as its very good elasticity properties. Generally PBT fibers are used in intimate, ready-to-wear, active and sportswear apparels, swimwear, carpets, automotive and home upholstery applications. Seamless technology is capable to meet the needs of consumers with performance, functionality and comfort. This technology has some advantages over the cutting and sewing. Seamless technology improves the aesthetic value and comfort, fredom of body movement, gives softness to the garment and minimizes the surface friction of the seams. In seamless machines, gloves, hats, socks, sweaters, sportswear can be produced. PBT fibers can be used in seamless sport wears, tights and intimates. These fibers provide more elasticity, comfort and softness on seamless sportswear than polyester fibers due to their good elasticity properties. In seamless technology polyester fibers generally are used with other fibers such as nylon, elastane. In this study, PBT/Nylon blend knitted seamless fabrics were dyed with disperse, acid and metal complex dyes at 98 o C in one bath. The color strength, colorimetric properties and fastness properties (rub and wash fastness) of these fabrics are investigated and compared. Moreover, the comparison of water comsumptions and costs of one and two baths dyeings are given on this study.