Celesticetin is an antibiotic produced by Streptomyces caelestis. We recently re-examined culture filtrates of S. caelestis for antibiotics and detected and extracted several bio-active materials in addition to celesticetin. The bioactive materials were extracted from clear filtrates with methylene chloride at alkaline pH (ca 8.0); after removing celesticetin by crystallization as the salicylate salt, partial separation of the remaining bioactive components was achieved by counter double current distribution and silica gel chromatography, yielding four bioactive compounds. These compounds were identified as desalicetin (structure II), celesticetin B (structure III), celesticetin C (structure IV), and celesticetin D (structure V, desalicetin acetate ester at the primary hydroxyl group C-2'), with their chemical structures and physicochemical properties (molecular formula, specific rotation, IR, UV, MS, NMR spectra, potentiometric titration data, etc.) characterized. These antibiotics have similar in vitro antibacterial spectra, mainly active against Gram-positive microorganisms; celesticetin C was as active as celesticetin in the in vitro system used, celesticetin B had 25% of the celesticetin activity, while desalicetin was the least active. The present preliminary communication describes the properties of these four antibiotics produced by S. caelestis.