Allicin was synthesized for the purpose of identification an dquantitation of a pharmaceutical dosage form in soft capsules. The identified transformed products fro allicin were dially disulfide , 3-vinyl-[4H]-1, 2-dithiin and 2-vinyl-[4H]-1, 3-dithiin in gas chromatrographic conditions and dially disulfide and ajoene in HPLC. Allicin is thermally unstable , it may be completely decomposed to vinyl dithiin isomers in GC conditions. For that reason, allicin was not found directly in the pharmaceutical dosage forms. In HPLC conditions, mobile phase was methanol /water containing 0.1% formic acid(65/35) and column was $mu$-Bondapak C18. Detection wa-velength was 254nm. The retention time of allicin was 6.98min. The calibration ranger for allicin was 10 $mu extrm{g}$/ml to 200$mu extrm{g}$/ml and correlation coefficient(r) was 0.987.