Objective: This study was done to investigate the relationship between existential anxiety and demoralization syndrome in predicting psychological well-being in patients with cancer. 
Methods: This correlational study was done on 57 patients with cancer (skin, breast, and stomach) aged 20-40 years, referring to hospitals in Ardabil selected by purposive sampling. The selected individuals completed the existential anxiety, demoralization syndrome, and psychological well-being questionnaires. To analyze the data, the stepwise regression analysis was used.
Results: The results showed a significant negative correlation between the existential anxiety and predicting psychological well-being in patients with cancer (P<0.01) and also a significant negative correlation between demoralization syndrome and prediction of depression in patients with cancer (P<0.01).
Conclusion: According to the results of this study, people facing life-threatening illnesses, such as cancer experience existential concerns, such as death anxiety, uncertainty, absurdity, and loneliness and the aim of psychotherapy and counseling interventions in these people is to create a supportive atmosphere that helps these patients to accept the disease, and consequently improve their mental health.