Quantitative and qualitative studies on the microflora in the faeces of 10 female koalas, Phascolarctos cinereus, were conducted with specific reference to 'pap', a special maternal faeces consumed by the juvenile at about the time of first emergence from the pouch. This specific coprophagy, called 'pap feeding', occurred multiple times in all of the females examined. Pap was higher in water content (81.8%) and pH (7.0) than normal faeces produced by the females before and after pap feeding (54.6-56.4% and 5.5, respectively), suggesting that it is derived directly from the contents of the caecum. Pap had higher (23-41-fold) viable counts of tannin-protein-complex-degrading enterobacteria (T-PCDE) than the normal faeces; in four of the females examined, viable T-PCDE were found in pap but never in the normal faeces. The evidence indicates that pap feeding is an essential physiological activity for the juvenile koala to prepare it for an imminent dietary transition from maternal milk to tannin-rich eucalypt leaves.