Nebivolol has been adequately tested in clinical efficacy trials of patients with mild hypertension. Clinical efficacy trials or their metaanalyses did not accurately predict the outcome of subsequent large studies. The primary objective was to assess the efficacy/safety of nebivolol 5–10 mg daily in a nationwide study of patients with mild hypertension. Secondary objectives were (1) to compare efficacy/safety as monotherapy versus add-on therapy and (2) to assess the effect of nebivolol on ISH. This was an open-label, 6-week follow-up study of 6356 patients with mild hypertension or ISH, as defined by the 1999 World Health Organization guidelines, recruited from 2700 facilities. Previous monotherapies were continued except for beta-blockers. Results are reported as means±SDs. Intention-to-treat analysis is given. A total of 5740 patients completed the study; of the withdrawals, 90% were lost for follow-up or were noncompliant, 38% were untreated before, 23% had beta-blockers. In the accumulated data, mean systolic and diastolic blood pressures fell by 24±14 and 13±9 mm Hg (both P<0.001). The differences between the blood pressure-reducing effects of nebivolol monotherapy and add-on therapy were not statistically significant: 28±16 and 22±14 mm Hg for systolic and 15±11 and 11±8 mm Hg for diastolic blood pressures. Adverse events were limited to 0.5% of the patients, no serious adverse events were observed. In the ISH patients, diastolic blood pressure fell by 4±6 mm Hg compared with 15±10 mm Hg in the no-ISH patients (P<0.01). Efficacy-safety effects of nebivolol in patients with mild hypertension can be generalized in a nationwide assessment. The efficacy of nebivolol as monotherapy and as the efficacy as add-on therapy are very similar. Nebivolol is highly efficacious in patients with ISH.