This single-center, open-label, single dose, randomized, two-way cross-over study will evaluate the pharmacokinetics, safety and tolerability of RO4917838 in healthy Chinese volunteers. Subjects will be randomized to receive a single oral dose of either 10 mg or 20 mg RO4917838 and, after a washout period of at least 21 but no more than 35 days, will be re-dosed with the alternative treatment. Anticipated time on study is up to 70 days.

Inclusion Criteria:

• Healthy Chinese male and female volunteers, 18 to 45 years of age inclusive at time of screening
• Healthy status is defined by absence of evidence of any active or chronic disease or disorder following a detailed medical and surgical history and a complete physical examination
• Body mass index (BMI) 19 to 28 kg/m2 inclusive

Exclusion Criteria:

• Pregnant or currently lactating females
• History of any clinically relevant disorder
• Any history of depressive episodes or treatment with antidepressants
• History of drug abuse within the past 2 years or positive results for drugs of abuse at screening or Day -1
• Alcohol dependence or history of this within the past 2 years or positive results for alcohol breath test at screening or Day -1
• Positive for HIV, hepatitis B or hepatitis C infection
• Regular smoker with consumption of more than 10 cigarettes a day or equivalent amount of tobacco
• Participation in a clinical study with an investigational drug or device within the last 3 months prior to dosing
• Medical history of significant drug allergies