This study is to compare the efficacy and safety of increasing doses of SLV306 with amlodipine.

Inclusion Criteria:

• sitting office diastolic blood pressure between 90 and 109 mmHg
• office systolic blood pressure between 140 and 179 mmHg
• mean day-time diastolic 24-h ABPM blood pressure >= 85 mmHg inclusive at baseline

Exclusion Criteria:

• known secondary hypertension
• decompensated congestive heart failure