Objective To compare the clinical efficacy of two β -adrenoceptor antagonists (bisoprolol and metoprolol) in the treatment of essential hypertension using ambulatory blood pressure monitoring (ABPM). Methods Eighty -eight patients with essential hypertension were enrolled in the study. The patients were randomly divided into Bisoprolol group (n=44) and Metoprolol group (n=44). Bisoprolol group was given Bisoprolol (2.5~5mg/d) and Metoprolol group was given Metoprolol (50~200mg/d) for 12 weeks. The diurnal changes of blood pressure, day time and night time, every time point of 24h ABPM were monitored. Results At the end of the 12th week, the mean systolic blood pressure (SBP)/DBP of 24h, day time and night time were dropped markedly in the two groups. In bisoprolol group SBP/DBP were decreased at every time point of 24h ABPM during the treatment. In metoprolol group, the SBP/ DBP was decreased at every time point of 24h ABPM during the treatment, but during the 23~24th hour the decrease did not have statistical significant difference (P 0.05). Conclusions Bisoprolol (2.5~5mg/d, once a day)can keep blood pressure smoothly decrease for 24h, but metoprolol (50~200mg/d, twice a day) can smoothly decrease blood pressure only for 22h in some patients.