Airway anatomy and physiology are altered in obesity, and an understanding of these changes is key to appropriate airway management. Longitudinal studies of pulmonary function have shown reduction in pulmonary tests with obesity. The functional residual capacity (FRC) is reduced by the conduct of general anaesthesia. In the obese, the resting metabolic rate, oxygen consumption and also carbon dioxide production are all increased, compounding the reduction in FRC. In addition to acting as an oxygen store, FRC is important in splinting small airways. Respiratory mechanics are affected even in moderate obesity. Prediction of difficulty: Mallampati score and neck circumference are better predictors than body mass index (BMI) and a history of obstructive sleep apnoea (OSA), but their predictive value is not strong. Difficult mask ventilation and difficult intubation are uncommon. Awake intubation is worthwhile if difficulty is expected, because of the rapid desaturation problem.