The tongue-repositioning manoeuvre (TRM) is a method to place the tongue in direct contact with the hard palate. The TRM makes use of voluntary generation of negative interocclusal pressure controlled by an intra-extraoral pressure indicator device in combination with an oral shield. The aim of the study was to investigate whether the TRM influences vertical tongue position and/or tongue-velum contact. Ninety consecutive patients (75 males, aged 26-76 years, and 15 females, aged 36-70 years) who presented with snoring and/or obstructive sleep apnoea (OSA) were examined at the University of Göttingen. Two cephalograms, with and without the TRM, were taken and traced. The data were analysed using Wilcoxon matched-pairs signed-rank test. Evaluation of the TRM demonstrated a significant increase (P < 0.01) of the mean tongue-velum contact from 6.3 to 24.5 mm and a significant decrease (P < 0.01) of the mean tongue-palate distance (12.3-3.1 mm) measured perpendicular to the nasal line. This was compatible with an intensification of posterior mouth closure and a contact position of the tongue with the palate.