Nine new pamamycin homologues were isolated from the culture broth of Streptomyces alboniger IFO 12738 using a combination of ODS and NH2 HPLCs, and their structures determined by GC-MS. The structural differences in these homologues are in the numbers and positions of methyl and ethyl groups. The aerial mycelium-inducing and growth-inhibitory activities in S. alboniger of these homologues and their antibiotic activity against Bacillus subtilis were examined. The effects of the alkyl substituents on these activities are discussed.