There are various structural parameters (number of filament, cross-sectional shape, linear density, etc.) determined during the production of synthetic fibre and these parameters influence product features. Among these parameters, cross-sectional shape of fibres has a significant importance. Desired features can be added to the products by varying the cross-sectional shape and in this way; new products with improved features or with high added value can be produced. As a consequence, studies on this subject have increased recently. In this study, the effects of different cross-sectional shapes and yam linear density on the features of polyester partially oriented yarn (POY) have been investigated. Five different cross-sectional shapes named round, trilobal, tetra, hexsa and octolobal and two different linear densities have been used in the study. Tenacity-elongation and unevenness tests have been applied onto yams. As a result of the study, it was seen that round, tetra and octolobal cross-sectional shapes lead to production of yam with high tenacity and breaking elongation while trilobal and hexsa leads to production of yam with low tenacity. In addition, due to its deep-channelled structure, hexsa cross-sectional shape led to POY yam structure with a high unevenness rate. It was also seen that an increase in the rate of linear density decreased the tenacity and breaking elongation rates of yarn and reduced POY unevenness.