OBJECTIVE: We aimed to assess how often and for what reasons general practitioners (GPs) consider older drivers medically unfit to drive. METHODS: All GPs certified to carry out fitness-to-drive assessments in Geneva (medical assessors, n = 69), as well as a random sample of 500 GPs practising in Vaud, Neuchatel and Jura, were asked to complete a questionnaire about the mean number of assessments per week, the number of negative decisions in the previous year and the main reason for the most recent negative decision. RESULTS: Completed questionnaires were returned by 268 respondents (45 medical assessors and 223 other GPs, participation rate: 47%). The mean proportion of drivers with a negative decision was 2.2% (standard deviation [SD] 3.3). The proportion was slightly lower among medical assessors (1.1%, SD 1.3) compared to other GPs (2.3%, SD 3.3, p <0.001). The main reasons for being considered medically unfit to drive were cognitive (64%) and visual acuity impairments (18%). CONCLUSIONS: GPs in this survey reported considering approximately 2% of older drivers as medically unfit to drive, mainly because of cognitive and visual acuity impairments. Further research should identify how GPs decide if older drivers are fit or unfit, and assess the effectiveness of medical screening in reducing car crashes involving older drivers.