Background,  Mobile phone is now an integral part of secondary school students ' daily life and for the majority, make student dependent on existing features and application for example students who are dependent on calculator application use their smartphone to get the answer. The study aimed to:  evaluate the effect of an intervention program for secondary students toward unhealthy use of mobile phones. Design: A quasi-experimental study was applied to achieve the aim of the current study. Setting: This study was conducted at Ali Mubarak school in Beni - Suef city Subjects: Consisted of 136 female students. Tools: one tool used to collect the data consists of 4 parts, a socio-demographic questionnaire, a knowledge questionnaire, an effect questionnaire, and a practice questionnaire. Results: before the implementation of the program a very limited number of students (3.7%, %, 4.4%)  had good knowledge about mobile phones and electromagnetic waves, while after implementation of the program the major number ( 80.9%, %,82.4%)  of the sample become had good knowledge, the most of the total sample(  44.1%, 66.2% and 69.1% ) had the high effect of physical and psychosocial respectively. While after the implementation of the program become very limited number from the total sample         (3.7%, 1.5%, and 2.2%) had a high effect, the major number (86.0% and 80.9%) of students had unsatisfactory reported practices when receiving calls and charging a mobile phone, respectively. After the intervention of the program, the most number (80.9% and 83.8%) of them had satisfactory reported practices for the same items respectively. Conclusion: There was a statistically significant improvement in students' knowledge, effect, and practice post-program. Recommendations: school can organize educational programs for refreshing and increasing knowledge and skills and practice for students about healthy use of mobile phones.