Obstructive sleep apnoea (OSA) is a condition whereby patients experience obstruction of their airways and develop an irregular breathing pattern during their sleep. If untreated, OSA can cause a variety of health problems, including high blood pressure, heart problems, difficulty concentrating, excessive sleepiness and an increased risk of having a motor vehicle accident. One widely recommended form of treatment for OSA is CPAP (continuous positive airway pressure), which consists of a pump which blows air into a patient's nose and/or mouth during sleep to hold open the airways and stop obstructions from occurring. The pump is connected to the patient via a connecting hose and an "interface" which rests on the patient's face. There are many different types of interface available for CPAP use, including masks which cover the nose, the mouth, both the nose and mouth, and even the entire face. Unfortunately, patients will often experience side effects related to their interface, which may make them want to stop their CPAP treatment. This review compares the different interface options for CPAP in patients with OSA. Four trials involving 132 people were included. Two studies compared nasal masks with an oral mask called the Oracle, and there did not appear to any significant differences between the two in terms of compliance, sleep study recordings, sleepiness or other symptoms of OSA. One study assessing nasal masks versus nasal pillows (consisting of prongs that rest within the nostrils) showed that patients using the nasal pillows had fewer overall side effects and reported greater satisfaction. The nose mask performed better than the face mask (which covers both the nose and mouth) with one study showing greater compliance and less sleepiness, and was the preferred mask in almost all patients. The choice of interface for a particular person will need to be tailored to the individual. Further trials comparing the many interfaces for CPAP in the treatment of OSA are needed.