A solid-phase microextraction (SPME) method has been developed for the quantitative analysis of sufentanil from human plasma by gas chromatography-mass spectrometry (GC-MS). The immersion SPME sampling technique was optimized for the extraction of sufentanil from plasma. The influence of the pH and the ionic strength of the sample on the extraction of the analytes by the SPME fiber were investigated. Sufentanil and fentanyl (internal standard) were extracted from plasma with a 65-microm polydimethylsiloxane-divinylbenzene (PDMS-DVB) fiber for 30 minutes using salting out agents in basic conditions. The calibration curve was linear over a concentration range of 6-50 ng/mL. Intraday and interday relative standard deviations were 3.6% and 10.6%, respectively. The limit of quantification was 6 ng/mL for a plasma volume of 1 mL. With regard to selectivity, simplicity, and low cost, the SPME method described should be useful for a rapid extraction of sufentanil from human plasma.