Yarn hairiness is an important element of total quality control. Zweigle system and its different versions are widely used commercially in the industry for the determination of yarn hairiness and these devices are only on hairiness. The measurement sensor on them classifies the hairs according to their length. In this research, Zweigle G567 and Uster Zweigle HL400 using the hairiness length classification system were compared. The most important difference between the two devices is that the recommended measuring speed for Uster Zweigle HL400 is eight times higher than Zweigle G567. In the study, thirteen yarns in different structures were used. The hairiness results in each mm were evaluated statistically in the SPSS program. It was observed that there were significant differences between the measurement results of two devices. In the literature, it is stated that there is an increase in the number of hairs with the increase in test speed of the Zweigle series hairiness devices. However, it was found in this study that there was a decrease in the number of hairs in most of the yarns measured in HL400 that use higher test speed. The more surprising result was that the strong correlation was determined between G567 and HL400 although the hair number obtained from devices show significant differences. This shows that the devices gave correlated results according to its operating principle, but the results of two devices operating at different speeds should not be compared with each other on the same test parameters.