Objective: Adherence to continuous positive airway pressure (CPAP) therapy for obstructive sleep apnoea (OSA) is poor. We assessed the effectiveness of a motivational interviewing intervention (motivational interview nurse therapy [MINT]) in addition to best practice standard care to improve acceptance and adherence to CPAP therapy in people with a new diagnosis of OSA. Method: One hundred six Australian adults (69% male) with a new diagnosis of OSA and a clinical recommendation for CPAP treatment were recruited from a tertiary sleep disorders center. Participants were randomly assigned to receive either 3 sessions of a motivational interviewing intervention (MINT; n = 53; mean age = 55.4 years) or no intervention (control; n = 53; mean age = 57.74 years). The primary outcome was the difference between the groups in objective CPAP adherence at 1-month, 2-month, 3-month, and 12-month follow-ups. Results: Fifty (94%) participants in the MINT group and 50 (94%) participants in the control group met all inclusion and exclusion criteria and were included in the primary analysis. The number of hours of CPAP use per night in the MINT group at 3 months was 4.63 hr and was 3.16 hr in the control group (p = 0.005). This represents almost 50% better adherence in the MINT group relative to the control group. Patients in the MINT group were substantially more likely to accept CPAP treatment. Conclusions: MINT is a brief, manualized, effective intervention that improves CPAP acceptance and objective adherence rates compared to standard care alone. (Contains 4 tables and 2 figures.)