<jats:p>Two new sesquiterpene isothiocyanates (1) and (3), together with the known sesquiterpene isothiocyanates (2) and (4) and the sesquiterpene isonitrile (5), have been identified as the antimicrobial components of Acanthella pulcherrima. The isothiocyanate (1) is enantiomeric to epipolasin-A (6), and thus provides the first reported occurrence of an enantiomorphic pair among the group of marine natural products characterized as sesquiterpene isothiocyanates.