Lipids from Chlorella vulgaris were successfully extracted using an ionic liquid, [Bmim] [MeSO4]. [Bmim][MeSO4] dissolved C. vulgaris, leaving the lipids insoluble. The undissolved lipids could easily be recovered due to the lower density of the lipid phase. Furthermore, ultrasound irradiation highly enhanced the extraction rate and yield with [Bmim][MeSO4]. The total amounts of lipid extracted from C. vulgaris by the Soxhlet method and the Bligh and Dyer's method were 21 and 29 mg/g dry cell weight (DCW), respectively, whereas it was 47 mg/g DCW with [Bmim][MeSO4]. Additionally, the amount of lipid extracted using [Bmim][MeSO4] was 1.6 times greater with ultrasound irradiation. The rate of extraction of lipids from C. vulgaris with [Bmim][MeSO4] was also 2.7 times greater with ultrasound irradiation. The fatty acid profiles of the lipids extracted using [Bmim][MeSO4] were very similar to those of the lipids obtained by Bligh and Dyer's method. (C) 2013 Elsevier Ltd. All rights reserved.