BACKGROUND: The study aims to determine the impact of cancer on Moroccan patients of Moslem faith. METHOD: Patients included a convenience sample with histological confirmed cancer. Cases with cerebral metastasis or lacking capacity were excluded. Participants were assessed prospectively using a questionnaire covering epidemiological and socio-economic characteristics, religious affiliation, repercussions of disease on religious beliefs and practices. RESULTS AND CONCLUSIONS: One thousand and six hundred patients (median age 49 years) were approached; 41% females and 74% from rural areas. There was a high rate of illiteracy (38%) and only 7% had higher education. Seventeen per cent were divorced, among whom 41% were divorced after diagnosis of cancer. Eighty-seven per cent had no medical insurance. All were Muslims; 49% practising believers and 51% non-practising. In the first group cancer represented a divine test that permitted acceptance of the disease. In the second group of 'non-practising believers', patients reported a feeling of culpability and 95% of them started taking up religious practices, often with extremism and sometimes in contradiction of medical advice. In both groups new behaviours were noticed; 450 women now wore the 'Hijab' (scarf), 19% used popular medicine and plants in their diet recommended by the Koran. While these results require replication they indicate changes in behaviour by those within the Moslem faith following a cancer diagnosis.