Pamamycin is a new antibiotic isolated from Streptomyces alboniger ATCC 12461. The antibiotic is active in vitro against Gram-positive bacteria, Neurospora, and Mycobacteria. The compound also acts as a streptomycete differentiation effector. It stimulates aerial mycelia formation in the producing organism. The new antibiotic of elemental composition C₃₆H₆₃NO₇
is completely different from puromycin, also produced by this strain. The present communication deals with the isolation, properties, and preliminary characterization of pamamycin.