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. CONCLUSIONS : The essential oil may reduce the pain or discomfort in the perineum region in patients with CP/CPPS. (Registration No. ChiCTR-IPR-14005448).