Hairiness is one of the character of the yarn affects many properties of the fabric such as handle, heat conduction, etc. Hairiness also leads to creation of pills on the fabric surface during usage of cloth. This fault is a serious problem in clothing industries. Thus it is of very importance to study the parameters causing the hairiness and to measure and control these parameters. The aim of this work is to investigate on the effect of blend ratio of the polyester/viscose yarn on the hairiness of the knitted fabric in abrasion process. The effect of weaving structure of the fabric on the hairiness was also studied. 9 different types of blended yarns were produced using open end spinning system. The blend ratios were; 0/100, 12.5/87.5, 25/75/, 37.5/62.6, 50/50, 62.5/37.5, 75/25, 87.5/12.5, 100/0, polyester/viscose respectively. The produced yarns were then used on a flat knitting machine. Three types of weaving patterns i.e. simple interlock, half cardigan and half milano were used and knitted fabrics were prepared. The surfaces of the prepared fabrics were scanned and images saved. The fabric types were then processed in an abrasion machine under 125, 500, 1000, 1500 and 2000 turns. After the abrasion process the surface of the fabrics were again scanned. The scanned images processed with image analysis technique the indices of the hairiness were determined. The obtained results were analyzed with the statistical methods. The results showed that the increasing of the viscose ratio in blend causes the increasing of the hairiness of the fabrics before the abrasion as well as after the abrasion process. The results also revealed that the fabric with simple interlock weave has the highest value of the hairiness while the half cardigan shows the lowest hairiness.