A Study Evaluating the Gastrointestinal (GI) Safety and Tolerability of Aliskiren Compared to Ramipril in Essential Hypertension

Inclusion Criteria: * Male or female outpatients, 50 years of age and older with a diagnosis of essential hypertension * Successful high quality colonoscopy at baseline including visualization of the entire colon and the cecum as confirmed by a photograph and collection of the rectal and cecal mucosal biopsy samples * All rectal, colon or cecal polyps found at baseline colonoscopy must be completely resected endoscopically at the time of the procedure. * Patients who are eligible and able to participate in the study, and who consent to do so after the purpose and nature of the investigation have been clearly explained to them (written informed consent). Exclusion Criteria: * Previously treated in an aliskiren study. * Current evidence of inflammatory bowel disease, the presence of colonic ulcerations (or other indices of colitis of any type) or colorectal carcinoma including carcinoma in situ found at baseline colonoscopy. * History of gastrointestinal carcinoma, Crohn's disease, ulcerative colitis, microscopic colitis. * History of familial polyposis or hereditary nonpolyposis colorectal cancer. * History of confirmed diverticulitis within 12 months of Visit 1. * History of celiac disease (gluten intolerance). * History of or current evidence on the baseline colonoscopy of melanosis coli.