Background and Objective: The infant hospitalization crisis causes severe stress to the parents. The nursing staff can play an effective role in reducing the tension because of the close relationship they have with infant mothers. The main aim of this research was to determine the rate of anxiety in mothers of hospitalized infants and to determine the primary factors in order to reduce their tension. Materials and Methods: In this descriptive cross-sectional study, a total of 80 mothers were selected by convenient sampling. The questionnaire was designed based on researcher’s investigation and the pss:NICU pattern containing 8 demographic questions and 43 tension factor questions. The SPSS statistical software and descriptive and analytical statistical methods of T-test, ANOVA, and Pearson correlation were used for data analysis. Results: Our data indicates that mothers suffered a tension grade of 164.61 ±22. The highest tension score was related to the care methods with 33.37 ±7.4, and the lowest score was related to the staff behavior with 10.83 ±3. Conclusion: Our observations show that the majority of mothers face stress regardless of their demographic differences and that the highest stress factor was related to the care methods, and the lowest was related to staff behavior. Therefore, the nursing staff must be aware of the factors causing stress so that they can apply appropriate practices to decrease the complications.