A protocol for extracting the terpene trilactone bilobalide from Ginkgo biloba leaves using the cellulose-dissolving ionic liquid 1-butyl-3-methylimidazolium chloride ([C(4)mim]Cl) was developed. Extraction with [C(4)mim]Cl/MeOH (1:1 w/w) at 80 degrees C afforded bilobalide with a yield of 0.14% w/w, which was 1.4 times higher than that achieved using conventional MeOH at 80 degrees C (0.098% w/w).