Background/aim: Thoracic spine insufficiency is a subject of interest in neck problems. The aim was to investigate thoracic spinal curvature and mobility in subjects with and without chronic neck pain (CNP), cut-off points, and the relationship with pain. Materials and methods: Fifty-six patients with CNP (CNP group) and 53 healthy volunteers (control group) were included. Neck pain intensity of the patients was assessed by visual analogue scale and sagittal thoracic curvature and mobility of all participants were assessed by Spinal Mouse (Idiag, Fehraltorf, Switzerland). Results: Thoracic curvature was higher (P < 0.001) and mobility lower in the CNP group in comparison to the control group (P = 0.013). There was a positive correlation between pain intensity and thoracic curvature (r = 0.391, P < 0.001), while there was a negative correlation between pain intensity and thoracic mobility (r = -0.260, P = 0.006). For detecting neck pain, it was observed that the cut-off points for thoracic curvature and mobility were 45.5° and 30.0°, respectively. Conclusions: An increase in thoracic curvature of more than 45° and a decrease in mobility more than 30° may be critical for CNP patients.