Dyeing properties of different molecular sized disperse dyes, which are commerically used for dyeing polyester microfibre fabrics, were investigated in accordance with the changing dye concentration. The experiements were carried out in two separate steps by using a certain levelling agent. In the first step, the dyeing properties of two microfibre fabrics and a conventional polyester fabric were investigated using two disperse dyes. In the second step, the dyeing properties of different molecular sized disperse dyes were investigated by using two microfibre fabrics and nine disperse dyes. Dye uptake and colour values of different polyester microfibre fabrics were found to depend on the molecular size and concentration of the disperse dyes used for dyeing and also on the properties of the fibres and weave pattern. Increasing the dye concentration in the dyebath causes an increase in the colour value to a certain limit. Using the excess amount of dye in the dyebath does not always improve the colour values. The colour values (coordinates) can be developed to the limit of fibre saturation for dyes. The development of colour values shows different changes in different dye concentration range.