BACKGROUND: Cardiovascular autonomic dysfunction is associated with increased incidence of cardiovascular diseases. This population-based study explored whether low FEV(1) or low vital capacity (VC) is associated with autonomic dysfunction, as measured by spontaneous heart rate variability (HRV) and systolic BP variability (SBPV). METHODS: SBPV and HRV were recorded during 5 min of controlled breathing in men and women who were 70 years of age. FEV(1) and VC were recorded in 901 subjects. Of them, information on HRV and SBPV was available in 820 and 736 subjects, respectively. Measures of autonomic function, that is, SBPV in the low-frequency (LF) and high-frequency (HF) domains, HRV, and baroreceptor sensitivity (BRS), were studied in sex-specific quartiles of FEV(1) and VC. RESULTS: Low FEV(1) was associated with high SBPV in the HF domain. The mean SBPV-HFs were 5.2, 4.5, 4.1, and 3.8 mm Hg, respectively, in subjects with FEV(1) in the first (low), second, third, and fourth quartile (p < 0.001 [for trend]). This relationship persisted after adjustments for potential confounding factors. Low VC was significantly associated with high SBPV-HF in the crude analysis but not after adjustment for confounding factors. Neither FEV(1) nor VC showed any significant relationship with BRS, HRV, or SBPV in the LF domain. CONCLUSION: In this population-based study, low FEV(1) was associated with high SBPV in the HF domain. It is suggested that high beat-to-beat variability in BP could contribute to the increased cardiovascular risk in subjects with moderately reduced FEV(1).