In the course of our screening program for new bio-active compounds, a novel triazolopyrimidine antibiotic, essramycin (1), was obtained from the culture broth of the marine Streptomyces sp., isolate Merv8102. Structure 1 was established by intensive NMR studies and by mass spectra. The compound is antibacterially active with MIC of 2 to 8 microg/ml against Gram-positive and Gram-negative bacteria, while it showed no antifungal activity. The fermentation and isolation, as well as the structure elucidation and biological activity of 1 are described.