A novel lyase, combining hydratase and aldolase activity, that converts citral intomethylheptenone and acetaldehyde, was purified from spores ofPenicillium , citral lyase activitywas induced 118-fold by incubating nongerminating spores with the substrate, citral. This cofactor independent hydratase/aldolase, was purified and found tobe amonomeric enzymeof 31 lyasehas aKmof aVmaxof UÆmg )1 .