Objective: Type D personality is characterised by negative affectivity (NA) and social inhibition (SI), and is often associated with poorer physical and psychological health. However, the underlying mechanisms are unclear and the literature lacks longitudinal assessment. Therefore, the aim was to prospectively examine the relationships between Type D and physical symptoms, in addition to aspects of retrospective health. Design: An online questionnaire-based study (N = 535) with a one-year follow-up (N = 160) was conducted with healthy individuals (18–65 years). Type D was assessed as both a categorical and dimensional construct. Main outcome measures: Participants completed the Type D scale-14 (DS14), Hospital Anxiety and Depression Scale (HADS), Cohen–Hoberman Inventory of Physical Symptoms (CHIPS) and Perceived Stress Scale (PSS) at both phases. Retrospective health questions and the Social Readjustment Rating Scale (SRRS) were also completed at follow-up. Results: Type D was independently related to cardiac/sympathetic, metabolic, vasovagal, muscular and headache symptoms at baseline. At follow-up stressful events and anxiety mediated the relationships between Type D and particular symptoms. Type Ds were more likely to report poorer health, increased minor illnesses, work absences, and medical information seeking. Conclusions: Type D is associated with symptoms often linked to stress. Although the relationships appear to be primarily driven by NA, these findings support the theory of a stress-related mechanism potentially underpinning the Type D-health relationship. These findings contribute to the literature continuing to highlight Type D personality as a risk factor for negative health outcomes.