Essential hypertension is a widespread disease which affects one out of every three adults in the industrialized world. It contributes to cardiovascular disease development, a major and well established risk factor. A patient non compliant to drug therapy is recognized as one of the primary reasons for inadequate blood pressure control.

Inclusion criteria

• MSSBP> 140 mm Hg, and/or MSDBP> 90 mm Hg and currently treated with either valsartan 320 mg/ HCTZ 25 mg or amlodipine 10 mg/HCTZ 25 mg at end of core study

Exclusion criteria

• Premature discontinuation in the core study or failure to comply with the core study protocol
• Any patient that the investigator decides should not participate in the extension

Other protocol-defined inclusion/exclusion criteria may apply