The diet of the Nankeen Kestrel Falco cenchroides in Australia is fairly well known, but has rarely been quantified. We analysed stomach contents of dead Kestrels collected in the grounds of Brisbane Airport in 2011–2013 to determine the preferred prey of the Airport’s Kestrel population. Diversity of the prey items was quantified using Simpson’s and Shannon’s Indices, as well as a relatively new index, the Index of Relative Importance. The stomach contents of 17 Kestrels were examined, and 183 individual prey items identified. The majority of the prey items were orthopteran insects, which occurred in 94% of the sampled stomachs, and in greater numbers than any other prey taxon. The dominance of the diet by orthopterans indicates that this taxon is of high value to the resident Kestrels. We speculate that this importance may be related to the high numbers of orthopterans present on the Airport grounds, and their relative ease of capture in comparison with vertebrate prey. The diet of the Kestrels at Brisbane Airport is similar to that reported previously for this species. The data from this study may facilitate better management of the bird-strike threat from this species at the Airport in the future.