This randomized, double-blind, placebo- and active-controlled, parallel group study will evaluate the safety and efficacy of RO4917838 (bitopertin) in patients with acute exacerbation of schizophrenia. Patients will be randomized to receive either RO4917838 10 mg or RO4917838 30 mg or olanzapine 15 mg or placebo orally daily for 4 weeks as inpatients, with a 4-week follow-up period.

Inclusion Criteria:

• Adult patients, 18-65 years of age
• Diagnosis of schizophrenia (Diagnostic and Statistical Manual of Mental Disorders DSM IV-TR)
• Acute exacerbation which began within the prior 8 weeks
• Female patients must be surgically sterile or post-menopausal, or agree to use effective contraception for the duration of the study

Exclusion Criteria:

• Current psychiatric diagnosis other than schizophrenia
• Alcohol or substance dependence within 3 months or abuse within 1 month (except for nicotine)
• Electro-convulsive therapy (ECT) within the prior 6 months
• Previous treatment with RO4917838 or another GLYT inhibitor
• Current treatment with olanzapine, or previous treatment with intolerability or lack of response
• Treatment with long-acting injectable antipsychotic within 2 dosing intervals
• Treatment with > 2 antipsychotics within 3 months
• History of neuroleptic malignant syndrome
• Have treatment-resistant schizophrenia as judged by treating physician or have failed two trials according to criteria in protocol