<jats:title>Abstract</jats:title><jats:p>Enzymatic hydrolyzates from seed meals of 17 species of the genus<jats:italic>Lesquerella</jats:italic>, family Cruciferae, were examined for thiooxazolidones and volatile isothiocyanates. Quantitative estimates of the total volatile isothiocyanates, calculated as butenyl, ranged from 0.6 to 13.0 mg per g of solvent‐extracted meal. No thiooxazolidone was found. By means of paper chromatography, melting point, and X‐ray patterns of the thiourea derivatives, the volatile isothiocyanates, 3‐methylthiopropyl‐, 4‐methylthiobutyl‐, and 6‐methylthiohexyl‐, were shown to be present in the hydrolyzates from three species. Evidence for identity of isothiocyanates in hydrolyzates from the remaining species was obtained by paper chromatography of the thiourea derivatives.