Preclinical studies have shown that fresh garlic extracts, aged garlic, garlic oil and specific organosulfur compounds generated by processing garlic could alter carcinogen metabolism, inhibit tumor cell growth through induction of cell cycle arrest or apoptosis, or angiogenesis. In particular, recent studies have suggested that anticarcinogenic effects of certain garlic compounds may implicate at least in part a modulation of histone acetylation, a process involved in the regulation of gene expression, resulting from the inhibition of histone deacetylase activity. The aim of this review is to describe available data on sulfur compounds from garlic and histone acetylation and to discuss their potential for cancer prevention. Available data indicate that garlic compounds could inhibit histone deacetylase activity and induce histone hyperacetylation in vitro as well as in vivo. Sparse studies provide evidence of an involvement of histone acetylation in modulation of gene expression by diallyl disulfide and allyl mercaptan. These effects were observed at high concentrations. Further investigations are needed to determine if the HDAC inhibitory effects of garlic organosulfur compounds might play a role in primary cancer prevention at doses achievable by human diet.