A simple, rapid and sensitive method has been developed and validated for the simultaneous quantification of diallyl trisulfide (DATS) and diallyl disulfide (DADS) in rat blood by gas chromatography with electron-capture detection. The analytes were prevented from degradation by addition of acetonitrile and extraction with hexane before gas chromatographic separation. Two calibration curves for DATS were linear over the range of 10-500 ng/mL and 0.2-20 microg/mL, with typical r values of 0.9989 and 0.9993, respectively. Similarly, two calibration curves for DADS were linear in the concentration range of 50-5000 ng/mL and 1-30 microg/mL, with typical r values of 0.9989 and 0.9983, respectively. The limit of detection was less than 10 ng/mL for DATS and 50 ng/mL for DADS, and the assay was highly reproducible, considering the intra-, inter-day relative standard deviations (R.S.D.) below 12%. The developed procedure was successfully applied for the evaluation of the pharmacokinetics of garlic oil following iv administration at a single dose (10 mg) of garlic oil in rats. The results show that the developed method is suitable for pharmacokinetic and therapeutic purposes of DATS and DADS.