Primary dysmenorrhea is the most common gynecologic complaint and the leading cause of recurrent short-term university or work absenteeism among young female adults. The present study aimed to study the effect of heat application versus stretching exercises on relieving discomforts of primary dysmenorrhea among university student girls. Research design: A quasi-experimental. Sample: A purposive sample of 180 university student girls were randomly divided into 3 equal groups, (intervention groups: two groups (1&2) Stretching exercise and heat application group) and control group). Each group had 60 student girls. Setting: The study was conducted in the Faculty of Nursing at Benha University. Tools Three tools were used in this study; 1) A Structured Self-Administrating Questionnaire, 2) Assessment of studied sample symptoms of primary dysmenorrhea& 3)Numeric pain rating scale Results: There was no statistically significant difference between the three studied groups regarding dysmenorrhea associated discomfort symptoms ( lower abdominal pain and headache pre-intervention and pain radiating down the legs, fatigue in the third cycle) p-value >0.05 but there were highly significant differences during different phases of assessment regarding other dysmenorrhea associated discomfort symptoms. Also, there was a highly statistically significant difference between the three studied groups during different phases of assessment regarding severity, frequency and duration of dysmenorrhea p value< 0.001 and Stretching exercise was more effective than heat application and control group in reducing the severity, frequency and duration of dysmenorrhea