Sleep apnoea syndrome (SAS) is a common sleep disorder with a prevalence ranging from 5.9% to 79.2% in the European general population over 40 years of age, depending on the clinical symptoms and apnoea hypopnoea scoring criteria used . Despite its frequency, the fact that it is a significant risk factor for many common diseases, and a recent meta-analysis demonstrating that available treatments are effective, SAS remains underdiagnosed. Indeed, patients with sleep apnoea presenting with concomitant cardiovascular diseases often have no typical presentation pointing towards obstructive SAS . In various locations around the world, suspected SAS patients may find that accessing diagnostic examinations can be challenging. The average waiting time for a sleep study can vary from 2 to 48 months in industrialised countries. Nevertheless, in-lab full-night polysomnography (PSG) remains the ‘gold-standard’ for the diagnosis of SAS, despite the fact that it is time consuming, expensive and often not widely available . In certain countries, PSG is obligatory in the diagnostic work-up for SAS. Thus, targeting the patient population that is most likely to benefit from PSG would help to optimise the limited resources at hand. Recent studies have suggested that mandibular movements (MM) can be considered a surrogate for the measurement of respiratory effort during sleep and can estimate total sleep time (eTST), as well as sleep fragmentation. Thus, MM can be used to identify sleep-disordered breathing. In their study, MARTINOT et al. compared the respiratory disturbance index measured by MM (MM-RDI) and the usual respiratory disturbance index measured by PSG (PSG-RDI). They reported that the MM-RDI is highly concordant with the PSG-RDI: in patients with a moderate-to-high pre-test probability for obstructive SAS, a MM-RDI >13.5 per h has a false positive rate of 4.72–18.49% (95% CI) when detecting a PSG-RDI ⩾15 per h, and a false negative rate of 0.0–16.82% (95% CI). Our objective was therefore to assess the feasibility of use of the MM-RDI as a screening tool in an ambulatory setting for PSG candidates. In order to address this question, we report herein the results of a preliminary study based on the retrospective analysis of a large, anonymous patient database in Belgium.