The structures of six novel spirodihydrobenzofuranlactams I~VI (1 ~6) were determined by spectroscopic methods.Six novel spirodihydrobenzofuranlactams I ~ VI (1 ~ 6) (Fig. 1) have been identified in extracts of two different Stachybotrys species as antagonists of endothelin and as inhibitors of HIV-1 protease. In a recently published paper1} we described the fermentation, isolation and biological properties of these secondary metabolites 1 ~6. Besides this novel class of the spirodihydrobenzofurans including the lactams 1 ~4, 6 and the imide 5 the known spirodihydrobenzofuranalcohol L-67 1 7762) was isolated. This inositol-phosphate phosphatase and HIV- 1 protease inhibitor L-671776 is structurally related to K-763) and to the described avian myeloblastosis virus inhibitors Mer-NF5003B, E (7) and F4). In this paper we will present the structure elucidation and physico-chemical properties of the spirodihydrobenzofuranlactams 1 ~ 6.