Background: Ophthalmological trauma is a serious public health problem that may cause vision loss, mono-ocular visual disability and non-congenital mono-ocular blindness in children because of their immature motor skills and natural curiosity. Aim of study: Was to evaluate the effect of designed guidelines on mothers' knowledge and practice regarding care of their children with ophthalmological trauma. Design: A quasi- experimental design was utilized. Setting: The study was conducted at inpatient department at Specialized Ophthalmology Center affiliated to Benha University Hospital. Sample: A purposive sample of 80 mothers of children with ophthalmological trauma who attended the inpatient department of Specialized Ophthalmology Center. Tools of data collection: Three tools were used to conduct the study. I: Knowledge of mothers structured interviewing questionnaire. II: Medical and social characteristics of children and III: Care of ophthalmological trauma observational checklists which include eye care, application of hot and cold compresses, eye drops instillations, eye ointment application and eye irrigation. Results: There was a highly positive statistical correlation between mothers' total knowledge and their total practice scores at pre/ post-guidelines. Conclusion: The research hypothesis was accepted and the majority of studied mothers had adequate knowledge and satisfactory practice post implementation of designed guidelines as compared to pre designed guidelines with highly statistically significant improvement. Recommendations: The nursing roles should be directed toward educating mothers about proper care for children with ophthalmological trauma.