The determination of $alpha$-pyrrolidone in ginseng extract by gas liquid chromatography (GLC) was established. $alpha$-Pyrrolidone in extract was tentatively identified by comparison of the relative retention time of sample peak with those of reference compound and coinjection noted peak enhancement. The .alpha.-pyrrolidone peak elimination was demonstrated by formation of oxime when treated with excess of NH$_{2}$OH ${cdot}$ HCl and NaOH, allowed to stand at room temperature for 5 minute. The elimination was also observed when samples were treated by the same procedure. The above method was proved to be useful for the determination of $alpha$-pyrrolidone in ginseng extract and in ginseng extract mixed with 51 plant extracts.