The effects of cross-sectional shape on the properties of cationic dyeable poly(ethylene terephthalate) fibres were investigated. Three different cross sections, namely tetra channel, snowflake and hollow, were used. Tensile test results showed that the hollow cross section has the highest breaking strength, while the snowflake has the lowest. In terms of thermal properties, no significant difference was observed. However, some differences in their morphology and surface topography were seen. According to birefringence studies, the hollow cross section has the highest overall orientation, while tetra has the lowest. In addition to this, hollow cross section gives the highest roughness value.