目的探讨长期、小剂量两地那非治疗难治性勃起功能障碍(ED)的机制。方法回顾性分析2004年12月至2005年10月间我院门诊收治的37例难治性ED患者临床资料。结果37例患者都完成了6周小剂量两地那非治疗。服药2周后勃起功能改善明显。第6周完成治疗后疗效满意,34例(91．89％)患者IIEF- 5评分、勃起硬度达到正常;停药后第2周及第6周复诊,33例患者疗效维持,4例稍有下降。结论长期服用小剂量西地那非治疗难治性ED患者疗效良好,其机制仍待探讨、证实。 Objective To investigate the mechanism of long-term and low-dose treatment of refractory erectile dysfunction (ED). Methods The clinical data of 37 patients with refractory ED who were admitted to our hospital from December 2004 to October 2005 were analyzed retrospectively. Results All 37 patients completed the 6-week low-dose placebo treatment. Erectile function improved significantly after taking medicine for 2 weeks. After 6 weeks of treatment, the curative effect was satisfactory. In 34 patients (91.89%), the IIEF-5 score and erectile stiffness reached normal. At week 2 and week 6 after treatment discontinuation, the efficacy of 33 patients was maintained and 4 patients were slightly decline. Conclusion Long-term use of low-dose sildenafil treatment of refractory ED patients with good effect, the mechanism remains to be confirmed.