Background: Primary care physicians provide palliative home care. In cancer patients dying at home in the Netherlands (45% of all cancer patients) euthanasia in about one out of every seven patients indicates unbearable suffering. Symptom prevalence, relationship between intensity of symptoms and unbearable suffering, evolvement of symptoms and unbearability over time and quality of unbearable suffering were studied in end-of-life cancer patients in primary care. Methods. 44 general practitioners during three years recruited cancer patients estimated to die within six months. Every two months patients quantified intensity as well as unbearability of 69 symptoms with the State-of-Suffering-V (SOS-V). Also overall unbearable suffering was quantified. The five-point rating scale ranged from 1 (not at all) to 5 (hardly can be worse). For symptoms assessed to be unbearable the nature of the suffering was additionally investigated with open-ended questions. The final interviews were analyzed; for longitudinal evolvement also the pre-final interviews were analyzed. Symptom intensity scores 4 and 5 were defined to indicate high intensity. Symptom unbearability scores 4 and 5 were defined to indicate unbearable suffering. Two raters categorized the qualitative descriptions of unbearable suffering. Results: Out of 148 requested patients 51% participated; 64 patients were followed up until death. The SOS-V was administered at least once in 60 patients (on average 30 days before death) and at least twice in 33 patients. Weakness was the most frequent unbearable symptom (57%). Pain was unbearable in 25%. Pain, loss of control over one's life and fear of future suffering frequently were unbearable (89-92%) when symptom intensity was high. Loss of control over one's life, vomiting and not being able to do important things frequently were unbearable (52-80%) when symptom intensity was low. Unbearable weakness significantly increased between pre-final and final interview. Physical suffering, loss of meaning, loss of autonomy, experiencing to be a burden, fear of future suffering and worrying more frequently occurred in patients suffering unbearably overall. Conclusions: Weakness was the most prevalent unbearable symptom in an end-of-life primary care cancer population. Physical suffering, loss of meaning and loss of autonomy more frequently occurred in patients who suffered unbearably overall. © 2013 Ruijs et al.; licensee BioMed Central Ltd.