Study Comparing SPP100 (Aliskiren) 150mg to Placebo and to Losartan 50mg in Patients With Mild to Moderate Essential Hypertension

Inclusion Criteria: * Age: 20 - 75 years old * Gender: Male or female * Status: Outpatients * Mild to moderate essential hypertension Exclusion Criteria: * Pregnant women, lactating mothers, women suspected of being pregnant, or women who wish to be pregnant * Patients with msSBP \>==180 mmHg and/or msDBP \>=110 mmHg at Visit 1, 2 or 3 * Patients with or suspected of having secondary hypertension (due to aortic coarctation, primary aldosteronism, etc.) * Patients suspected of having malignant hypertension Other protocol-defined inclusion/exclusion criteria may apply