Objective: To assess whether folic acid supplementation ameliorates hot flushes. Design: Double-blind, placebo-controlled randomised trial. Setting: Nine hospitals in England. Population: Postmenopausal women experiencing ≥50 hot flushes weekly. Methods: Women (n=164) were randomly assigned in a 1:1 ratio to receive folic acid 5mg tablet or placebo daily for 12 weeks. Participants recorded frequency and severity of hot flushes in Sloan Diary daily and completed Greene Climacteric and Utian Quality of Life (UQoL) Scales at 4-weekly intervals. Main Outcome Measures: The change in daily Hot Flush Score at week-12 from randomisation based on Sloan Diary Composite Score B calculation. Results: Data of 143 (87%) women was available for the primary outcome. The mean change (SD) in Hot Flush Score at week-12 was -6.98 (10.30) and -4.57 (9.46) for folic acid and placebo group, respectively. The difference between groups in the mean change was -2.41 (95% CI: -5.68, 0.87), p=0.149 and in the adjusted mean change was -2.61 (95% CI: -5.72, 0.49) with p=0.098. There was an increased benefit in the folic acid group regarding changes in total and emotional UQoL scores at week-8 when compared with placebo. The difference in the mean change from baseline was 5.22 (95% CI: 1.16, 9.28) and 1.88 (95% CI: 0.23, 3.52) for total and emotional score, respectively. Conclusions: Folic acid had a greater benefit in reducing Hot Flush Score over 12 weeks in postmenopausal women when compared with placebo; however, the difference did not reach statistical significance. Definitive evidence of benefit requires a larger study.