A multi-agency investigation followed the notification of four locally acquired human brucellosis cases in north-west NSW. Feral pig hunting within a geographically discrete region was identified as the likely exposure with Brucella suis the suspected cause. To test whether feral pigs in the region were infected with Brucella, serological testing was performed on trapped feral pigs and testicular abscesses from condemned carcasses bound for export were cultured. Although no Brucella species were identified in the feral pigs tested in NSW, Leptospira species were. Strengthening of human surveillance and ongoing collaboration between animal and human health agencies is required to confirm that Brucella suis causes brucellosis in humans and feral pigs in north-west NSW.