Objective:To evaluate the efficacy and safety of essential oil treatment for type Ⅲ chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS).Methods:A randomized controlled trial was conducted from December 2014 to October 2015.Seventy type Ⅲ CP/CPPS patients were assigned to the essential oil group (35 cases) or almond placebo oil control group (35 cases) by a random number table.The oil was smeared by self-massage on the suprapubic and sacral region once a day for 4 weeks.The National Institutes of Health Chronic Prostatitis Syndrome Index (NIH-CPSI) and expressed prostatic secretions (EPS) were examined.The primary outcome was NIH-CPSI pain domain.The secondary outcomes included other NIH-CPSI domains and laboratory examinations of EPS.Adverse events were also observed.Results:Sixty-six subjects completed the full 4-week treatment.There was no significant difference between almond oil control and essential oil groups in terms of the total score of NIH-CPSI,pain,quality of life and urination domain scores of NIH-CPSI and EPS examinations (P＞0.05).In the essential oil group,pain between rectum and testicles (perineum) in the domain of pain or discomfort was significantly reduced at week 2 and week 4 compared with almond oil control group (P＜0.01).No serious adverse events occurred.Conclusion:The essential oil may reduce the pain or discomfort in the perineum region in patients with CP/CPPS.(Registration No.ChiCTR-IPR-14005448)