The purpose of this study is to collect the long-term (12 months) safety data on aliskiren 300 mg when taken in combination with HCTZ 25 mg.

Inclusion Criteria:

1. their successful completion of the CSPP100A2302 core study with at least eight months combination treatment of aliskiren 300 mg and HCTZ 25 mg, i.e., patients who received aliskiren 300 mg and HCTZ 25 mg at Month 4 of the core study and complete the core study.
2. absence of ongoing severe adverse events at Visit 10.