The content of the sternal gland secretion from four male koalas (Phascolarctos cinereus) was analyzed using gas chromatography–mass spectrometry. Volatile fatty acids, aldehydes, ketones, mono- and sesquiterpenes were identified, together with various volatile nitriles and oximes, some of which had not previously been described from any mammalian skin gland. Benzyl cyanide and phenylacetaldehyde oxime were identified as major components of the secretions, together with smaller amounts of the novel 3-methylthiopropanal oxime. The relative abundance of the identified compounds was highly variable between individuals and the scent composition was found to be partly determined by the scent of surrounding conspecifics. Principal component analysis revealed a high similarity between related individuals.