Garlic ( Allium sativum ), apart from its use as food, has been used as a medicinal plant for over 4000 years. Several investigations suggest that the biological and medical functions of garlic are due to the high content of organosulphur compounds. The bioaccessibility of the organosulphur compounds is an important factor for the evaluation of the functional activity of the garlic. In the present study, a Dynamic Gastrointestinal Digester (DGD) was used to determine the bioaccessibility after digestion of two extracts containing the organosulphur compounds; ajoene and allicin. The DGD is a multi-compartmental, dynamic and computer-controlled system, which reproduces the gastrointestinal digestion process including the chewing, the gastric digestion and the digestion of the small intestine phases. The study showed that after an in vitro gastrointestinal digestion process, ajoene is seven times more bioaccessible when encapsulated than in unencapsulated doses, recovering approximately 51% of the compound administered. Allicin recovered after digestion, administered as a combination of alliin and alliinase, showed no significant difference in bioaccessibility when comparing unencapsulated and encapsulated doses. The allicin recovered after the gastrointestinal digestion in both cases exceeded 40%. The results show significant bioaccessibility of the two organosulphur compounds after in vitro gastrointestinal digestion, which enables the prediction of their behaviour in the gastrointestinal tract. The stability of the unencapsulated allicin-potential formulation is also promising for whole gut availability. Future work is recommended to understand the absorption of the compounds for a better understanding of their possible beneficial effects in human health.