Authentication　is　a　basic　mechanism　for　secure　roaming　in　wireless　Mesh　networks　(WMNs).　However,　existing　roaming　authentication　protocols　such　as　3G,　IEEE　802.1x,　etc.　cannot　meet　the　requirement　for　secure　and　fast　network　access　in　response　to　rapid　increase　in　the　size　of　networks　and　in　the　number　of　users.　In　this　paper,　we　propose　an　instant　authentication　scheme　for　secure　roaming　in　WMNs　in　which　information　exchange　between　a　visited　network　and　the　home　network　is　not　required　for　inter-network　roaming　authentication.　To　achieve　the　goal,　the　security　scheme　relies　on　an　elaborate　design　of　the　public　key　distribution　plan.　Furthermore,　a　user　needs　to　authenticate　with　the　authentication　center　of　the　visited　network　only　once　on　the　first　visit　to　the　network.　Our　simulation　results　show　that　the　proposed　scheme　performs　better　in　authentication　latency　as　well　as　in　security　when　compared　to　some　existing　roaming　authentication　methods.　©　2009　IEEE.