Background:Spiritual wellbeing (SWB) of nurses working in oncology wards is directly related to quality of care they provide. An increase in their SWB might lead to decrease in their spiritual distress and increase in their coping strategies. The aim of this study was to investigate the impact of a spiritual care program on SWB of nurses.Materials and Methods:This study is a clinical trial with before and after intervention groups, which was carried out on 65 nurses in Omid Hospital in Isfahan in 2017. Nurses were randomly assigned into control (n = 34) and intervention groups (n = 31). The data were collected through demographic and SWB scales. Spiritual care program consisting of eight sessions of four relationship-based domains, including relationships with God, self, others, and the environment, were carried out in the intervention group. Two care training sessions in oncology departments were conducted for the control group.Results:The results indicated that the differences in SWB mean scores between the intervention and control group after treatment were statistically significant (t = 2.58, p = 0.012). Also, SWB mean scores in the intervention group before and after treatment showed a statistically significant difference (t = 2.86, p = 0.008).Conclusions:The results showed that the spiritual care program might have a positive impact on the SWB of nurses working in oncology wards. Therefore, it is indispensable to promote and prioritize the SWB of nurses so that patients and their families will receive better health services.