The objective of this study is to evaluate the efficacy, safety, pharmacokinetics (PK) and pharmacodynamics (PD) of two different dosages of rivaroxaban in the treatment of deep vein thrombosis (DVT) and the prevention of the occurrence and the recurrence of DVT or pulmonary embolism (PE) in Japanese patients with acute symptomatic DVT without symptomatic PE.

The general design of the trial is open label between the Rivaroxaban and the reference arm. However, there are two groups in the Rivaroxaban arm only for the initial 3 weeks. Between these two groups and in this initial period, the study is blinded.

Inclusion Criteria:

• Men and women >/= 20 years of age in patients with confirmed acute symptomatic proximal deep vein thrombosis (DVT) without symptomatic pulmonary embolism (PE)

Exclusion Criteria:

• Thrombectomy, insertion of a caval filter, or use of a fibrinolytic agent to treat the current episode of DVT
• More than 48 hours pre-randomization treatment with therapeutic dosages of anti-coagulant treatment or more than a single dose of warfarin from the onset of the current episode of DVT to randomization
• Calculated creatinine clearance (CLCR) < 30 mL/min
• Subjects with hepatic disease which is associated with coagulopathy leading to a clinically relevant bleeding risk
• Active bleeding or high risk for bleeding contraindicating treatment with unfractioned Heparin (UFH) or warfarin
• Systolic blood pressure > 180 mmHg or diastolic blood pressure > 110 mmHg