Partial acetylation of oligomycin A (1) resulted in the formation of 5,9,33-tri-O-acetyl (2) and 5,9,13,33-tetraacetyl (3) derivatives whose structures have been established through complete assignments of their H-1 and C-13 NMR spectra. These derivatives were devoid of inhibitory activity when tested on Aspergillus niger spores.