We have recently re-examined culture filtrates of Streptomyces caelestis for antibiotics and detected several bio-active materials in addition to celesticetin. This preliminary communication describes the properties of four of these antibiotics: desalicetin, celesticetin B, celesticetin C, and celesticetin D. 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 using counter double current distribution and/or silica gel chromatography. The four compounds were isolated as hydrochlorides, and their structures were determined through IR, UV, NMR, and mass spectroscopy, along with molecular formula analysis, potentiometric titration, and comparisons with known substances. Desalicetin was identified as an intermediate in the biosynthesis of celesticetin. Celesticetin B, C, and D differ from celesticetin in the acyl group at the C-2' position of desalicetin: celesticetin B has an isobutyryl group, celesticetin C has an anthraniloyl group (C6H6NC-), and celesticetin D is desalicetin acetate. All four compounds exhibit similar in vitro antibacterial spectra, primarily active against Gram-positive microorganisms. Celesticetin C showed activity comparable to celesticetin, celesticetin B had 25% of celesticetin's activity, and desalicetin was the least active. In vivo evaluations of these antibiotics are incomplete. Additionally, S. caelestis produces other antibiotics such as desdanine, desdamethine, and ethesdanine (as previously reported), and further antibiotics from this culture are currently under investigation.