Novel antifungal antibiotics, designated as dactylfungins A (1) and B (3), were isolated from the culture broth of Dactylaria parvispora D500. Dactylfungins A and B were found to be new substances containing an a-pyrone and a y-pyrone ring, respectively, which conjoined with a polyalcohol moiety and a long side chain, based on NMR spectral analyses. The antibiotics were active against Candida pseudotropicalis and other fungi, with an MICvalue at less than 10 /ig/ml.In the course of our screening program for new antibiotics, two new antifungal antibiotics were isolated from the culture broth of Dactylaria parvispora strain D500 and designated as dactylfungins A (1) and B (3) (Fig. 1). This report describes the taxonomy of the producing organism, fermentation and isolation procedures as well as physico-chemical and biological properties of the new antibiotics.