New 5-lipoxygenase inhibitors, designated epocarbazolins A and B, were isolated from the culture broth of Streptomyces anulatus T688-8. These compounds showed potent rat 5-lipoxygenase inhibitory activity with weak antibacterial activity. Structural studies revealed that epocarbazolins are new carbazole antibiotics having a novel substitution pattern and an epoxide in the side chain.