A capillary gas chromatography/mass spectrometry (GC/MS) method for the quantitative analysis of arecoline in plasma has been developed for concentrations in the range 1-50 ng ml-1. Hexadeuterated arecoline was utilized as the internal standard. The removal of drug from plasma was accomplished by a two-step liquid/liquid extraction procedure involving a wash step followed by extraction with 5% triethyl amine in ethyl acetate. The GC/MS determinations were carried out with temperature-programmed capillary GC and ammonia chemical ionization mass spectrometry. The [M + H]+ ions of both analyte and internal standard were monitored at m/z 156 and 162, respectively. The method is linear and has sufficient sensitivity, precision, accuracy and selectivity for analysis of drug levels in human plasma.