This open-label, fixed sequence, two-period study will assess the effect of multiple dose carbamazepine on the single dose pharmacokinetics of RO4917838. Subjects will receive a single oral dose of RO4917838 on Day 1 of the 12-day study period 1 and, after a washout of 3-6 weeks, in study period 2 carbamazepine orally daily on Days 1-24 with a single oral dose of RO4917838 on Day 16.

Inclusion Criteria:

• Adult healthy male volunteers, 18-65 years of age inclusive
• Body mass index (BMI) 18-30 kg/m2 inclusive

Exclusion Criteria:

• History or presence of any disorder or condition that would render the subject unsuitable for the study, place the subject at undue risk or interfere with the ability of the subject to complete the study in the opinion of the investigator
• History of any significant cardiovascular, hepatic, renal, respiratory, gastrointestinal, endocrine, immunologic, allergic, dermatologic, hematologic, neurologic or psychiatric disease, or cancer
• Any confirmed significant allergic reactions against any drug, or multiple allergies in the judgment of the investigator
• Native Asians or subjects with Asian racial origin