—Dysmenorrhea is the most common complaint in pediatric and adolescent gynecology. Most adolescent girls exhibit some degree of pain and discomfort during menstrual period, which can impact on their daily activities, and disturb their productivity at home or at their school. This study was a quasi experimental design aiming to evaluate the effect of nursing intervention program on self care of adolescent girls with dysmenorrhea through: assessing the adolescent girls' knowledge and self care practices, developing and implementing nursing intervention program according to adolescent girls' needs, and evaluating the improvement in adolescent girls' knowledge and self care practices after implementation of the program. Setting: This study was conducted at pediatric and obstetric outpatient clinics in Benha University Hospital, Teaching Hospital. Sample: The sample consisted of 100 adolescent girls. Data were collected through an interviewing questionnaire designed to collect data about socio-demographic characteristics of adolescent girls, their menstrual history, menstrual characteristics, knowledge about dysmenorrhea and self care practices through asking questions toward dysmenorrhea. The results of this study revealed that the mean age of studied sample was 14.3 ± 1.5.A significant improvement in the adolescent girls' knowledge and self care practices toward dysmenorrhea after implementation of the nursing intervention program. The study concluded that the designed nursing intervention program has positive impact on improving the adolescent girls' self care toward dysmenorrhea. The study recommended that establish intervention programs to improve self care of adolescent girls with dysmenorrhea regarding nutritional aspects, exercises, and healthy behaviors, and mass media focuses to increase adolescent girls awareness about dysmenorrhea as TV and radios.