Abstract Objective: To describe the contents and structure of the social representation of cancer. Method: A qualitative study based on the Theory of Social Representations, carried out in a High Complexity Care Unit in Oncology. Data collection included a socio-occupational and clinical characterization questionnaire and free evocations form from 100 cancer patients in chemotherapy treatment and in-depth interviews with 29 of them. The analysis was performed using EVOC software. Results: One hundred (100) patients participated in the study. The social representation of cancer has the words normal, difficult disease, death and fear in its central nucleus. The apparent ambivalence between the continuity of life and its finitude as structuring meanings of this representation enables establishing an inferential hypothesis that relates normal disease to the possibility of treatment, control and cure of cancer, while the fear of death remains in the representational field linked to the disease, which has a difficult treatment to cope with. Conclusion: The social representations of cancer based on the presented interrelationships provide reflections which may contribute to increasing the individual and social care of patients with malignant neoplasm and their family in health services.