To examine the efficacy of Clinacanthus nutans extracts in treatment of Herpes genitalis and Herpes zoster from randomised clinical trials (RCTs). Bibliographic databases, including MEDLINE, EMBASE, CINAHL, Cochrane CENTRAL, AMED, WHO trial registry, http://www.clinicaltrial.gov, Thai Index Medicus, and Index Medicus Siriraj library, were searched from their inception dates to February 2010 without language restrictions. Methodological quality of included trials was assessed using Jadad's quality scale and Cochrane's risk of bias. Four RCTs (n=286) met our inclusion criteria which include two studies on H. genitalis and the other two on H. zoster; in these studies, a total of 151 patients were assigned to the C. nutans group of H. genitalis trials, a pooled relative risk of C. nutans preparations against placebo for a 3 day-full crusting was 6.62 (95% C.I. 3.83-11.47) and of a 7-day complete healing was 3.77 (95% C.I. 2.46-5.78). In H. zoster, the relative risk for a 3 day-full crusting was 3.21 (IQR 0.97-10.58). This meta-analysis and systematic review suggests some beneficial effects of C. nutans preparations on treatments of H. genitalis and H. zoster. However, more robustly designed trials are needed to substantiate the benefit of these plants, specifically on their active purified compounds, and their potencies and benefits on treatment outcome of H. genitalis and H. zoster.