One hundred young females with primary dysmenorrhea will participate in this study. They will be recruited from the Gynecological outpatient clinic, Kasr El Ainy University Hospital, Cairo, Egypt.

All females should have regular menstrual cycles. Taking blood samples of 3 ml through the cubital vein to examine the levels of serum progesterone will be carried out on the 21st day of menstruation, while to assess the pain intensity of primary dysmenorrhea using the Visual Analogue Scale (VAS) and physical and psychological symptoms associated with dysmenorrhea will be assessed by menstrual symptoms questionnaire

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Blood samples will be taken by physician for each girl, and will send to laboratory center to measure the progesterone level in the blood. The normal serum progesterone level at 21st day is 4-20 ng

It will be measured by Visual analogue scale. It is 10 cm line with values ranging from 0 to 10. 0 indicates no pain nd 10 indicates the worst pain.

It will be measured by menstrual symptoms questionnaire. It is 25 items split into two categories which used to assess the physical and psychological symptoms associated with dysmenorrhea. The score on each item ranged from 1 (never) to 5 (always) with a higher composite score indicating more symptoms

The correlation between serum progesterone level and pain intensity measured by the VAS will be conducted

The correlation between serum progesterone level and menstrual symptoms measured by the menstrual symptom questionnaire will be conducted