Two new desulfated yessotoxin (YTX) analogues were isolated from a toxic batch of Adriatic musselscollected in October 2004. Their stereostructures were elucidated through extensive NMR and MS-basedanalysis. The finding of these desulfocarboxyhomoYTXs in shellfish poses additional problems to thoseinstitutions entitled to control seafood safety, since desulfated YTXs fail the European Union methodcurrently in force for checking toxicity in mollusks.