This study is an 18-week study to evaluate the tolerability of nebivolol compared to metoprolol ER in outpatients with mild to moderate hypertension taking HCTZ. It is a multi-center, randomized, double blind (DB), active-control, parallel-group study, starting with a 4-week HCTZ run-in phase, followed by a 12-week DB treatment phase. Patients meeting the entry criteria at the end of run-in are randomized to one of two treatment groups, nebivolol or metoprolol ER. Uptitration of dose of study drug will occur if needed during the first 4 weeks of the DB phase, after which there is an 8-week stable-dose period of treatment. A 2-week double-blind withdrawal phase follows, during which tapering off study drug occurs.