Severe obstructive sleep apnea (OSA) is a risk factor for mortality. The ability of continuous positive airway pressure (CPAP) therapy to mitigate this increased risk of death has not been studied in Chinese adults. The objective of our study was to compare mortality in Chinese patients with simple snoring, untreated OSA, and OSA treated with CPAP. We recruited adults with OSA or simple snoring from our sleep medicine clinic. OSA was diagnosed using standard polysomnography. Subjects were followed at least annually for a mean of 8.9 years (SD 1.9). CPAP compliance was checked with the built-in meter. We then assessed all-cause mortality. Five hundred fifty simple snorers, 257 with untreated mild OSA, 316 with untreated moderate OSA, 457 with untreated severe OSA, and 235 with mild to severe OSA treated with CPAP were included. Simple snorers had a much lower mortality rate (2.98 per 1000 person-years [95 % CI, 2.93 to 3.02]) than the untreated severe OSA group (11.07 per 1000 person-years [95 %CI, 10.86 to 11.29]; P < 0.0001). Compared with simple snorers, fully adjusted mortality was highest in the untreated, severe OSA group (hazard ratio [HR], 3.51 [95 %CI, 1.93 to 6.39]). Treatment of severe OSA patients with CPAP eliminated this increase in mortality (HR, 0.81[95 %CI, 0.36-1.86]). Severe OSA significantly markedly increases the risk of death in Chinese patients and CPAP treatment with adequate compliance reduces this risk.