A new phenazine antibiotic, DOB-41, was isolated from the culture broth of a Pseudomonas strain. The antibiotic obtained as yellow crystals showed UV maxima at 255 nm and 370 nm. A molecular formula, C19H18N2O6, was indicated by elemental analysis and mass spectrometry. The structure was elucidated by X-ray diffraction analysis. The antibiotic exhibited inhibitory activity against Gram-positive bacteria, and antitumor effect against leukemia P388 in mice.