Alliin is a predominant flavor precursor in garlic cloves. It interacts with the enzyme alliinase when garlic cloves are crushed, cut, or chewed to produce allicin, an unstable thiosulfinate that is the main biologically active component of fresh crushed garlic. Biological functions and health benefits of garlic include reduction of cancer risk in humans, improving immune system, and anti-microbial, anti-oxidant, and anti-hypertensive activities. The quality of fresh garlic and garlic products is usually related to its alliin content and allicin release potential. This research presents a simple, rapid, and precise HPLC method for alliin determination. It involves the use of 30:70% methanol: water and 0.05% sodium dodecylsulfate mobile phase composition, C18 5 μm disc column of size 3.9 x 150 μm, and detector set at 210 nm. The method showed good reproducibility with 0.56%-4.11% relative standard deviations, a linear response of peak area to alliin concentration of 0.4 ng/mL-80 ng/mL, and average recovery of 93.5%-101%. Determination of alliin in eight garlic samples indicated the highest amount in garlic tablet that was expected. The method presented is economical and efficient and can be used in alliin determination. The method gave a satisfactory chromatograms with methanol-hydrochloric acid extract but not with hot water extract.