Background. The birth of a premature baby needing to be hospitalized in the neonatal intensive care unit (NICU) endangers the initial mother-baby relationship, affecting mother-baby attachment. Therefore, it seems necessary to provide mothers of premature babies with appropriate nursing support. In the present study, we aimed to investigate the effects of spiritual self-care training on the mother-baby attachment of mothers giving birth to premature babies hospitalized in the NICU. Methods. This was a semi-experimental study with pre-test/post-test design conducted on 60 mothers with babies admitted to the NICU of Taleghani Hospital of Ilam (30 participants in each of the intervention and control groups).Two questionnaires were used for data collection, including a demographic information questionnaire and the Maternal Postnatal Attachment Scale (MPAS). Five self-care training sessions (45 minutes each) were held for mothers of the intervention group according to a self-care booklet prepared by the researcher. The attachment questionnaire was again completed after one week of the last training sessions by all participants, and the data were analyzed using SPSS version 22 software. Descriptive statistics were used to present quantitative (mean ±SD) and qualitative (frequency, %) variables. The normality of the data was checked using the Kolmogorov Smirnov test, and the MANOVA and univariate analysis of covariance (ANCOVA) tests were used to investigate the effects of the training on mother-baby attachment. The statistical significance level was considered P<0.05. Results. The means of the total attachment score in the intervention and control groups were obtained as 51.73 and 56.43 at the pretest and 53.36 and 49.77 at the post-test, respectively, indicating that spiritual self-care training was effective in improving mother-baby attachment (P<0.05). Conclusion. Our results showed that spiritual self-care training augmented mothers’ attachment to their babies hospitalized at the NICU. According to the results of the present study, it is suggested to pave the ground in clinical environments by educating nurses and caregivers and supporting the mother and the baby through spiritual self-care interventions to promote maternal attachment and improve their conditions. Practical Implications. According to the results of the present study, it is suggested to pave the ground in clinical environments by educating nurses and caregivers and supporting the mother and the baby through spiritual self-care interventions to promote maternal attachment and improve their conditions.