Snoring and obesity are together highly predictive of obstructive sleep apnoea. Obesity, when associated with hypoventilation, in the absence of other conditions that can explain the hypoventilation, equates with the obesity-hypoventilation syndrome. Each condition has its own clinical ramifications, which have been discussed in this chapter. This chapter also incorporates a systematic evaluation of the obese snorer and provides a methodical approach for the screening for various associated and contributory conditions and treatable traits. A discussion on the obesity hypoventilation syndrome is also included.