The composition of isothiocyanates in Dolsan leaf mustard was investigated. Five major volatile isothiocyanates detected in leaf mustard were sec-butyl isothiocyanate, allyl isothiocyanate, 3-butenyl isothiocyanate, n-hexyl isothiocyanate and β-phenylethyl isothiocyanate. In both leaf and leaf stalk allyl isothiocyanate and 3-butenyl isothiocyanate were the most abundant. The compositional difference of isothiocyanates between leaf and leaf stalk was that n-hexyl and β-phenylethyl isothiocyanates were present more in leaf than leaf stalk.