This prospective, single-arm, pilot clinical trial, developed to evaluate the efficacy and tolerability of mirtazapine for alleviating hot flashes, was conducted between May 2001 and January 2002. Patients' baseline characteristics were collected during the first week of the study. At the beginning of the second week, patients were started on mirtazapine at a dose of 7.5 mg at bedtime. The dose of mirtazapine was then increased to 15 mg at week 3 and to 30 mg at week 4. For week 5, patients could choose whether to take 15 mg/d or 30 mg/d. Data were obtained primarily from patient-completed questionnaires. Data from 22 evaluable women were available. For the 16 patients who completed the study, the median reductions in total daily hot flashes and weekly hot-flash scores from their baselines were 52.5% and 59.5%, respectively. Patients reported improvements in tension, trouble sleeping, abnormal sweating, distress from hot flashes, satisfaction with hot-flash control, overall quality of life, and impact of hot flashes on quality of life. Patients also reported increases in appetite and dry mouth. Although data from a double-blind, placebo-controlled clinical trial would be necessary to more definitively elucidate the efficacy and toxicity of mirtazapine in patients with hot flashes, the available data suggest that mirtazapine is a reasonable treatment to consider in patients with hot flashes, particularly in those with anxiety and sleep disturbances.