In the course of searching for metabolites related to emestrin (3) from Emericella striata (80-NE-22), dethiosecoemestrin (1) was isolated from the methylene chloride extract of the culture filtrate. The tremorgenic mycotoxin, paxilline (6), was also isolated from the mycelial extract. The structure of dethiosecoemestrin was established on the basis of the chemical and spectroscopic evidence as 1. It is postulated that dethiosecoemestrin was biogenetically derived from emestrin.Dethiosecoemestrin was easily degradated to violaceic acid (5). The antimicrobial activity of dethiosecoemestrin was examined.