In submerged culture, Emericellopsis minima (Stolk) I.M.I. 69015 produced a substance resembling 6-aminopenicillanic acid in its behaviour on paper chromatograms and in its properties after reaction with phenylacetyl chloride. The substance was destroyed by penicillinase but was acid-stable. The culture also produced cephalosporin N and two unidentified antibiotics which have been named emericellopsin A and B. When other fungi of the genera Emericellopsis and Cephalosporium were examined in a similar manner, C. salmosynnematum and Cephalosporium I.M.I. 49137 were also found to produce small amounts of a substance resembling 6-aminopenicillanic acid. Examination of Emericellopsis minima (Stolk) also showed the presence of penicillin amidase activity in this culture.