The aim of this study was to validate the French-language version of the Type D personality scale-14 among general and clinical populations (acute coronary syndrome and breast cancer patients). The two-factor structure of the Type D personality scale-14 was confirmed by factorial and confirmatory analyses. Internal consistency for both subdimensions of Type D personality scale-14 (negative affectivity and social inhibition) was very good with α = .87 for each. Contrary to our expectations, the Type D prevalence was much higher in the breast cancer group than in the acute coronary syndrome patients. In conclusion, the French-language Type D personality scale-14 showed good psychometric properties among general and clinical populations.