We have screened microorganisms isolated from soil and plants for their ability to produce antitumor antibiotics and isolated a new glycosidic pyrrolo(1,4)benzodiazepine antibiotic named DC102 from a cultured broth of a Streptomycete. In this communication, we report the production, isolation and characterization of DC 102. DC102 is a basic compound obtained as white powder. It showed the following properties: MP 120°C (dec); readily soluble in MeOH, EtOH, slightly soluble in H2O and Me2CO but insoluble in CHC13, n-hexane; UV λmax nm (ε) 210 (14,000), 244 (sh, 11,000), 310 (6,500); electron impact (EI)-mass m/z 429.2261 (M+ - CH3OH) (calcd for C23H31N3O5: 429.2242). The IR spectrum of DC 102 is shown in Fig. 1. The 13C NMR spectrum is given in Fig. 2. DC102 had a UV spectrum characteristic of pyrrolo(1,4)benzodiazepine antibiotics. It gave a positive reaction to β-anisidine, indicating the presence of a sugar moiety. However, its molecular formula is different from that of sibiromycin, the only aminoglycosidic pyrrolo(1,4)benzodiazepine antibiotic so far reported. DC102 exhibited weak antimicrobial activity against Gram-positive bacteria (Table 1). DC 102 was effective against murine leukemia P388, showing significant increase of life span (ILS 54%) at a dose of 0.5 mg/kg (Table 2). The LD50 value of DC 102 was 1.5 mg/kg (ip) in mouse. The detailed studies of the antitumor activity of DC 102 are in progress and will be published in due course.