In this study, we tested the ability of structure-related isothiocyanates to induce the antiatherogenic enzyme paraoxonase-1 (PON1) in cultured hepatocytes. Allyl isothiocyanate (AITC), phenylethyl isothiocyanate (PEITC), and sulforaphane (SFN), but not butyl isothiocyanate (BITC) resulted in dose-dependent induction of PON1 transactivation in Huh7 cells in vitro. Induction of PON1 due to AITC was inhibited by the selective peroxisome proliferator-activated receptor gamma-antagonist T0070907. AITC was used in a subsequent in vivo study in mice (n = 10 per group, Western-type diet) to test its PON1 inducing activity. Unlike in cultured hepatocytes, AITC supplementation (15 mg/kg body weight) did not increase hepatic PON1 mRNA and protein levels in mice. Thus, it is suggested that AITC may be a potent inducer of PON1 in vitro, but not in mouse liver in vivo.