Obstructive sleep apnoea (OSA) is a risk factor for stroke, but little is known about the effect of OSA and continuous positive airway pressure (CPAP) on the incidence of long-term, nonfatal cardiovascular events (CVE) in stroke patients. A prospective observational study was made in 223 patients consecutively admitted for stroke. A sleep study was performed on 166 of them. 31 had an apnoea/hypopnoea index (AHI) <10 events · h(-1); 39 had an AHI between 10 and 19 events · h(-1) and 96 had an AHI ≥ 20 events · h(-1). CPAP treatment was offered when AHI was ≥ 20 events · h(-1). Patients were followed up for 7 yrs and incident CVE data were recorded. The mean ± SD age of the subjects was 73.3 ± 11 yrs; mean AHI was 26 ± 16.7 events · h(-1). Patients with moderate-to-severe OSA who could not tolerate CPAP (AHI ≥ 20 events · h(-1); n = 68) showed an increased adjusted incidence of nonfatal CVE, especially new ischaemic strokes (hazard ratio 2.87, 95% CI 1.11-7.71; p = 0.03), compared with patients with moderate-to-severe OSA who tolerated CPAP (n = 28), patients with mild disease (AHI 10-19 events · h(-1); n = 36) and patients without OSA (AHI <10 events · h(-1); n = 31). Our results suggest that the presence of moderate-to-severe OSA is associated with an increased long-term incidence of nonfatal CVE in stroke patients and that CPAP reduces the excess of incidence seen in these patients.