Essential oils and cuticular waxes were extracted from peppermint leaves with supercritical carbon dioxide in a semicontinuous-flow extractor. The effects of CO2 flow rate and pressure on the extraction rate were studied within the how rate range of (4.1-9.8) x 10(-5) kg s(-1) and the pressure range of 10-30 MPa. Flow rate effect indicated that the intraparticle diffusion resistance was not dominant in this process. The extraction rate of cuticular waxes increased remarkably with the pressure, whereas that of essential oils was almost constant as compared with cuticular waxes. The concentration of cuticular waxes at the exit of the extractor was close to the solubility of triacontane while that of essential oils was much lower than the solubility of 1-menthol.