Background: The experience of cancer is highly stressful and potentially traumatic. We assessed the presence of Post‐Traumatic Stress Symptoms (PTSS) in long‐term cancer survivors and their caregivers, while examining the association between PTSS and clinical, demographic and psychological variables in the long term. Methods: In this cross‐sectional study 212 survivor‐family caregiver dyads completed measures of post‐traumatic stress symptoms (PTSS) (Impact of Event Scale), depression and anxiety (Hospital Anxiety Depression Scale). Coping strategies, fatigue, cognitive decline, stressful life events and psychopathological history were also assessed among survivors. Data were analyzed using mixed models, accounting both for individual and dyadic effects. Results: Cancer survivors and their caregivers were assessed after a mean of 6 years after treatment. Twenty per cent of survivors and 35.5% of caregivers had possible posttraumatic stress disorder (PTSD), while 23 patients (11.0%) and 33 caregivers (15.6%) had probable PTSD. Among cancer patients, the severity of post‐traumatic symptoms was associated with an anxious coping style, previous psychopathology and depression (p < 0.001), whereas among caregivers it was associated with depression and having a closer relationship with patients (p < 0.001). Patients’ depression was associated with caregivers’ intrusion symptoms. Conclusions: High levels of cancer‐related PTSS were still present several years after treatment in both survivors and caregivers. Psychopathology may derive from complex interactions among coping, previous disorders and between‐person dynamics.