Background: Hot flash is a common problem in climactric (time course around menopause)and menopausal period. The most effective treatment of it is HRT but There is a serious need for alternative therapies for hot flashes, as hormone replacement therapy (HRT) is associated with increased rates of breast cancer and heart disease.   Materials and Methods: This trial used a randomized, two-stage(4 weeks per stage), cross over methodology to study the efficacy of fluoxetin (20 mg/d) for treating hot flashes in menopausal women (who atleast had 14 hot flash attacks per week.) in first period, First group received 4 weeks of therapy with fluoxetine versus second group receiving placebo.during the next stage of treatment, patients were crossed over between two groups . The patients received no drug in the one week period interval between the two periods of study.(wash out).T-test, chi square, mann whitney, pair t-test, wilcocxon and fisher, tests were used for analysing data in spss software.   Results: Eighty randomized women began protocol therapy. By the end of the first treatment period, hot flash frequency decreased 55% in the fluoxetin arm versus 28% in the placebo arm. Cross over analyzing demonstrated a significantly greater marked improvement in hot flash severity with fluoxetin than with placebo (p=0/00).   Conclusion: Both Fluoxetin and placebo are effective in improving of hot flashs but fluoxetin is significantly more effective. So fluoxetine is a realistic althernative theray for women who do not wish to receive hormones for fear of cancer or other reasons.