ABSTRACT: BACKGROUND: In cancer care, a GP's work is rarely defined clearly. Our aim was to assess GPs' work with cancer patients in France and in Norway, where the roles of the GP and the organization of the system are rather different. FINDINGS: A questionnaire with 40 closed-ended questions about GP involvement in diagnosis, treatment, follow-up and terminal care was constructed and mailed to samples of GPs. The patients had seen the doctor at least once over the past year. In France 1679 and in Norway 386 individual patient questionnaires were completed. GPs have a major role in the diagnosis of cancer, and this role varies according to cancer type. The GPs participated actively in different phases of follow-up after cancer treatment. Low response rates do not allow direct comparison between countries, but higher PSA screening rates in France seem to increase the percentage of patients diagnosed after screening rather than after a clinical suspicion. Interaction between GPs and specialists during cancer treatment and follow-up was important in both countries. CONCLUSION: Both in France and in Norway GPs participate actively in cancer care. Early clinical diagnosis is a challenge. More research is needed about how GPs can improve their early diagnostic work. Organisational issues may influence cancer responsibilities for the GP, and national health systems should be challenged to look at possible new roles for GPs in cancer care. Medical training, both pre- and post-graduate, should prepare doctors for collaboration between primary and secondary care, particularly important in cancer care.