The purpose of the study was to assess polysomnographic indicators of increased mortality risk in patients with stroke or a transient ischemic attack (TIA). We performed polysomnographies in 63 acute stroke/TIA patients. Mortality data were collected from a national database after a 19-37-month follow-up period. Of the 57 stroke and 6 TIA patients, 9 stroke patients died during follow-up. All nine had moderate or severe sleep-related breathing disorders (SRBDs). Binarily divided, the group with the highest apnea hypopnea index (AHI) had an almost 10-fold higher mortality risk (hazard ratio (HR) 9.71; 95 % confidence interval (CI) 1.20-78.29; p = 0.033) compared to the patients with the lowest AHI. The patients with the longest versus shortest nocturnal wake time had a higher mortality (HR 8.78; 95 % CI 1.1-71.8; p = 0.0428). Lung disease increased mortality (HR 9.92; 95 % CI 2.00-49.23; p = 0.005), and there was a trend toward a higher mortality risk with atrial fibrillation/flutter (HR 3.63; 95 % CI 0.97-13.51; p = 0.055). In stroke patients, the AHI and nocturnal wake time are indicators of increased mortality risk. SRBDs in stroke patients should receive increased attention.