1. The metabolism of (+)-citronellal, (+-)-7-hydroxycitronellal, citral, (-)-perillaldehyde, (-)-myrtenal, cuminaldehyde, thujone, and (+-)-carvone was studied in rabbits. 2. In (+-)-7-hydroxycitronellal, (-)-perillaldehyde, (-)-myrtenal and cuminaldehydes, both primary alcohols and carboxylic acids were formed. 3. In (-)-citronellal and citral, regioselective oxidation was found and a trans-positioned methyl group was carboxylated in each case. 4. In o-cuminaldehyde, reduction but not oxidation, was found.