Sleep apnea (SA) is associated with an increased risk of cardiovascular outcomes in the general population. SA seems more prevalent in end-stage renal disease (ESRD) patients and may in part explain their higher risk of cardiovascular events. In a historical cohort study of 65 ESRD patients on chronic dialysis we studied the relationship between apnea-hypopnea index (AHI) and mortality and asked whether SA, traditionally defined as an AHI of 15 events per hour of sleep or more, increased the risk of death. SA was present in 63% of subjects; they were older (p=0.007), heavier (body mass index 27.9 +/- 6.2 kg/m 2) (p=0.0005), sicker (Charlson co-morbidity index) (p=0.03) and more likely to have diabetes causing ESRD (p=0.005). In multivariate analysis, only age (p=0.04) and baseline AHI (hazard ratio 1.33/15 units of AHI; 95% CI: 1.05--1.68; p=0.02) were significantly associated with mortality. Further studies are warranted to confirm those results.