Experiences of people living with cancer have revealed that spiritual well-being is a vital aspect of a healthy life, necessary for creating a positive psychology and will guide patients toward a meaningful life. It can also increase cancer patients' adaptability and improve their quality of life and survival. The present study aimed at determining the spiritual well-being among cancer patients and their nurses. This descriptive-cross sectional study carried out with a convenience sampling method and participation of 120 hospitalized cancer patients and their nurses in oncology units. Data were collected using Paloutzian and Ellison well-being questionnaire (r = 0.82) and were analyzed using, chi-square and t-tests by using SPSS 21. The average scores of religious, existential and spiritual well-being in patients were 52, 46 and 99 respectively. Their average scores of religious, existential and spiritual well-being in nurses were 29, 40 and 70 respectively which falls within an average range (41-99). Comparing spiritual well-being scores between patients and nurses using chi-square and t- tests showed a significant difference (p=0.001). Spirituality and positive psychology have always been considered as effective treatment for people who are suffering from cancer. Increased spiritual well-being among nurses can improve spiritual health in cancer patients.             Keywords: cancer patients, spiritual well-being, religious well-being, existential well-being, positive psychology, nurses.