Smart garment system is efficient for upper body movement monitoring during simple tasks. There is a lack of literature on smart textile garments being reliable for shoulder girdle motion assessment in advanced motor tasks such as high string performance. The aim of the article was to examine the reliability of the DAid Smart Shirt for Shoulder Girdle Motion Assessment during advanced motor tasks such as high string performance. Methods: 14 volunteer violinists aged 18.6 (SD 2.1) with a body mass index 20.05 (SD 2.3) were recruited. The violinists performed a legato bowing task. The DAid smart shirt worked as the assessment tool: a compression garment with textile strain sensors sewn onto it. Cronbach alpha coefficient, Interclass Correlation Coefficient were calculated to assess the within-session test-retest reliability. Results: An excellent and good result test-retest reliability was assessed in 57% of the violinists, for other 43%, the ICC and Cronbach alpha coefficient was less than 0.59. Conclusion: the DAid Smart shirt is reliable for shoulder girdle motion assessment during high string performance. The smart textile garment should be customized and suitable for the body in order to assess shoulder girdle motion during high level or advanced activities such as high string performance.