Background: Hospitalization of children is one of the main causes of anxiety and concern for families. Mothers of sick children need emotional support to provide effective care and adequate support for their children. Objectives: Thus, the present study was conducted to investigate the relationship between parental concerns and nursing support of hospitalized children. Methods: This descriptive cross-sectional study was conducted on 150 mothers of children admitted to the Pediatric Ward of Baqiyatallah Al-Azam Hospital in Ali Abad Katoul, Golestan province, Iran, in 2018. The children were hospitalized for at least 24 h, and were selected by the convenience sampling method. Concerns of mothers were measured by the Parental Concerns Questionnaire and nursing support was assessed by the Nursing Support of Parents Questionnaire through individual interviews. Data were analyzed by SPSS version 21 software at a significance level of 5%. Results: The mean scores of mothers' concerns and nursing support were 16.6 ± 5.6 and 72.01 ± 16.52, respectively. Pearson correlation coefficient showed a significant relationship between nursing support and mothers' concerns (r =-0.22, P = 0.004). Conclusions: Mothers' concerns are decreased by increasing nursing support. By identifying factors effective in decreasing mothers' concerns, the treatment team members, especially nurses, can play an important role in providing nursing care and support for mothers of hospitalized children. Therefore, increasing self-confidence of mothers and providing nursing support for them will increase the quality of care and satisfaction of patients and their caregivers, especially the mothers.