To date, the clinical use of unattended home-based polysomnography (PSG) is not recommended. To assess whether sleep efficiency is better at home, we have performed a prospective, crossover, single-blind study comparing unattended home- versus attended in-hospital PSG in a population referred for high clinical suspicion of obstructive sleep apnoea syndrome (OSA). Within 2 weeks, all the patients underwent both PSG performed by the same sleep technician, which were analysed by another blinded technician. Payments for each procedure were also calculated. Sixty-six patients (mean age: 49±13 years; mean body mass index: 30±7; mean Epworth Sleepiness Scale: 10±5) were included. The quality of recordings was poor in 1.5% of the attended PSG versus 4.7% for unattended PSG (P=0.36). Sleep efficiency at home was better (82% versus 75%, P