OBJECTIVE To compare serum estradiol (E2) level in Thai surgical menopausal women before and after receiving a daily dose of 1 mg oral micronized 17 beta-estradiol. METHODS Experimental study (before and after treatment). METHODS Gynecological ward, Hatyai regional hospital. METHODS 40 premenopausal Thai women who had undergone total abdominal hysterectomy with bilateral salpingoooporectomy (Surgical menopause) for 1 week previously due to benign gynecologic conditions were recruited in the present study. These women had no contraindications for receiving hormonal replacement therapy and no history of any hormonal intake in the past. METHODS All women were assigned to receive a 1 mg micronized 17 beta-estradiol (Estrofem, Novo Nordisk A/S, Denmark) orally applied at bedtime (08.00 p.m.) each day. METHODS Serum estradiol (E2) levels were measured before and after treatment at 4, 8 and 12 weeks. The hormonal measurement was performed using the ELFA-technique (Enzyme Linked Fluorescent Assay). RESULTS Four cases were excluded due to loss to follow up. Of the remaining 36 cases, the mean age (+/- SD) and the body mass index were 46.27 +/- 5. 74 years and 23.72 +/- 2.92 kg/m2, respectively. Serum E2 level significantly increased from baseline value at 4, 8 and 12 weeks (mean (+/- SD) of E2 level at 0, 4, 8 and 12 weeks: 3.82 +/- 6.30 pg/ml, 117.11 +/- 92.86 pg/ml, 135.28 +/- 91.38 pg/ml and 164.48 +/- 78.94 pg/ml, p < 0.05) respectively. CONCLUSIONS A daily dose of 1 mg oral micronized 17 beta-estradiolfor 12 weeks increased the serum E2 level to the follicular phase level of the normal menstrual cycle.