A series of compounds derived from 3-alkyl-N-hydroxysuccinimide have been synthesized and their inhibitory activity toward human leukocyte elastase has been investigated. Compounds having an isobutyl or isopropyl group at the C-3 position have been found to be particularly effective inactivators of the enzyme. The introduction of a trans-styryl group (as in compounds 16 and 18) results in a drastic enhancement in inhibitory activity indicative of ...