Introduction : Hot flashes are a common side effect of menopause on quality of life .One of the treatments for hormone replacement therapy is Phytoestrogens, so researchers were supposed to study the effect of flaxseed and soy on hot flashes that menopause do.

  Methods: A randomized clinical trial monitored 90 postmenopausal women who complain of hot flashes in Clinic of Arak city were divided in three group. in First group, daily 25 grams of flaxseed, a second group of 25 grams of soy and controls 25 g wheat flour for 8 consecutive weeks was given. lack of menstruation in the last 12 months, having normal blood pressure, lack of anxiety medications, antidepressants, hormones estrogen and progesterone in 6 months and Anticoagulant , and medications such as ibuprofen, and asthma and allergy were criteria for the inclusion of study and exclusion criteria of the study include: lack of proper use of herbal medicines, causing irritation and sensitivity to drugs and changing of their location. At begining, week four and week eight, the severity and frequency and statistical analysis were used.

  Results: Severity among treatment groups flaxseed, soybeans and wheat flour in the first, fourth and eighth weeks, has a significant difference, P= 0/000 However the three groups at the beginning, middle and end of the study there was no significant difference, start P = 0.653, in the middle P-value = 0.485 and the end of study s were P= ./409. Frequency was not significantly different between the three groups, but significant differences were observed in eight weeks and soybeans led to a lower frequency.

  Conclusion: The results showed that flaxseed and soy has redued number and severity of hot flashes in postmenopausal women and soybeans led to a lower frequency of hot .