The purpose of the study was to assess prevalence rates of pathological, problem and at-risk gambling in German- and Italian-speaking Switzerland in 2007, employing a DSM-IV-based instrument. A random sample of 4997 individuals participated in a computer-assisted telephone interview and 1388 of the individuals who refused to participate on the telephone interview completed a paper questionnaire. The total sample included 6385 participants; the return rate was 52.2%. Among the general population over 18 years of age, 2% engaged in lifetime at-risk gambling, 0.5% in problematic and 0.3% in pathological gambling. We found past-year prevalence rates of 0.7% of at-risk gambling, 0.1% for problematic and 0.02% for pathological gambling. These rates are lower than rates in previous Swiss studies. This may be due to measures to reduce false positive diagnoses such as employing the National Opinion Research Center DSM Screen for Gambling Problems (NODS) instead of the previously used SOGS, an instrument which was found to overestimate prevalence rates in general population up to 50%.