Zervamicins I and II are new polypeptide antibiotics produced by Emericellopsis salmosynnemata. Zervamicin I is an acidic compound while zervamicin II is a neutral polypeptide like emerimicins, antiamoebin and stilbellin to which both zervamicins are related. In a recent communication we reported the production of emerimicins II, III, IV by Emericellopsis microspora grown in a medium supplemented with trans-4-n-propyl-L-proline. Extending our studies with other Emericellopsis species we found that Emericellopsis salmosynnemata strain 336 produces several antibacterial agents without addition of trans-4-n-propyl-L-proline to the medium. Two of these compounds have been isolated crystalline and characterized. The production, isolation and characterization of these antibiotics, named zervamicins I and II, are the subject of the present communication.