The purpose of the study is to evaluate the efficacy and safety of SR58611A in patients with Generalized Anxiety Disorder. The primary objective is to evaluate the efficacy of a 700 mg dose of SR58611A compared to placebo in patients with generalized anxiety disorder (GAD).The secondary objectives are to evaluate the efficacy of SR58611A on disability and quality of life in patients with GAD and to evaluate safety of SR58611A.

The study is a multicenter, multicountry, randomized, parallel-group, double blind, placebo and paroxetine-controlled study consisting of three segments (A, B, and C). Segment A is a 1-week, placebo, single-blind period and Segment B is an 8-week, double blind period. All randomized patients must complete a post-study visit 1 week after intake of the last dose of study medication.

Inclusion Criteria:

• Out-patients, 18 to 65 years of age.
• Patients suffering from generalized anxiety disorder (GAD) as defined by Diagnostic and Statistical Manual of Mental Disorders, 4th Edition, Text Revision (DSM-IV-TR) criteria and confirmed by the Mini International Neuropsychiatric Interview (MINI) plus GAD Module.
• With a total score on the 14-item Hamilton Anxiety Rating Scale (HAM-A) ³ 20.
• Having given voluntarily their written informed consent to participate in the study.
• Able to comply with the protocol and follow written and verbal instructions.
• For inclusion into Segment B of the study, patients must fulfill the following criteria:
• All Segment A inclusion criteria.
• Completion of a minimum of 3 and a maximum of 9 days of treatment in Segment A.
• Not "placebo responders" (i.e., improvement £ 20 % on HAM-A total score between V1 and V2)

Exclusion Criteria:

• Patients with a diagnosis of Major Depressive Disorder as defined by DSM-IV-TR within 6 months of study entry.
• Patients with a Montgomery-Asberg Depression Rating Scale (MADRS) total score of 18 or higher at screening or baseline visits.
• Patients having a moderate to high current risk for suicide.
• Patients with other current anxiety disorder assessed with the MINI: agoraphobia, social phobia, panic disorder, obsessive-compulsive disorder, post-traumatic stress disorder, acute stress disorder.
• Patients with a lifetime history according to the MINI of: bipolar disorders, psychotic disorders, antisocial personality disorder.
• Patients with severe or unstable concomitant medical conditions according to the Investigator's judgment.
• Females who are pregnant or lactating.
• Female patients of childbearing potential must use an effective method of birth control during the entire study period.
• Patients with positive test for any illicit drug included in the urine drug screen.
• Participation in a clinical trial of an experimental therapy within 3 months prior to screening