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Objective: To investigate the effects of carvedilol therapy on autonomic cardiovascular regulation and baroreflex sensitivity, by short-term spectral analysis of heart rate (R-R) and systolic blood pressure (S-S) variability. Patients and Methods: The trial was conducted in 12 adults (seven men and five women, mean age 37 ± 7 years) with newly diagnosed hypertension. Patients were classified as having mild or moderate hypertension (stages I to II). R-R, S-S and respiratory signals were recorded during rest and after sympathetic activation by head-up tilt, before and after receiving a 15-day course of carvedilol (25mg once daily). Cross-spectral analysis of R-R and S-S signals was used to determine the baroreflex sensitivity index (α index). Results: At rest after carvedilol therapy, the R-R and S-S LF (low frequency) normalised units (nu) significantly decreased (p = 0.0002 and p = 0.003, respectively), while the HF (high frequency) component reciprocally increased. The R-R LF/HF ratio decreased significantly (1.28 ± 1.58 vs 0.41 ± 0.29, p = 0.008). The α index also increased significantly (12.04 ± 6.25 vs 16.05 ± 7.45, p = 0.002). During tilt, carvedilol therapy reduced the R-R and S-S LF (p = 0.0003 and 0.002, respectively), but preserved the LF increase normally induced by passive orthostatism, and significantly increased the α index (6.18 ± 1.97 vs 8.89 ± 3.29, p = 0.014). Conclusion: Our findings suggested that carvedilol attenuates cardiovascular sympathetic responsiveness and improves baroreflex sensitivity. [ABSTRACT FROM AUTHOR]