the aim of this study was to evaluate the relationship between cognition about illness and spiritual well being,and quality of life in 50 patients with terminal cancer in the city of medellin, colombia. the study used an exploratory, descriptive, correlational and cross sectional research design. the instruments used were the spirituality index of well-being siwb, the illness cognition questionnaire icq and the mcgill quality of life questionnaire mqol. descriptive results show that the more serious and insidious symptoms are body pain, asthenia and adinamia. regarding the total level of spiritual well-being, positive correlations were found with perceived benefits in the icq and existential well-being of quality of life;and negative correlations with helplessness in the icq and psychological symptoms of quality of life. in conclusion, spirituality and positive cognitions regarding aterminal disease process are mediating variables, buffers and modulators of the quality of life on the physical, psychological, emotional, social, spiritual and economic level.