The natural radiocarbon (14C) content of whole, gut voided Saccoglossus bromophenolosus collected in Lowes Cove, Maine, USA, was compared with that of a non-voided worm, sectioned individuals, and the natural product 2,4-dibromophenol (2,4-DBP) isolated from S. bromophenolosus. In all cases, the 14C content was greater than that of the sediment from which the enteropneusts were collected. The 14C content of 2 polychaetes, Glycera dibranchiata and Clymenella torquata, also collected from Lowes Cove, were similarly enriched in 14C compared to the bulk sediment. These results show that all 3 species consumed recently fixed carbon that was much newer than organic carbon in the bulk sediment. The value (+10.4‰) obtained for 2,4-DBP isolated from S. bromophenolosus in this study differs from that reported in a previous study (–170‰). The discrepancy is attributed to methodological differences. The importance of selecting an appropriate method when isolating compounds for natural abundance 14C analysis is discussed.