NSW has a putative malaria vector in Anopheles annulipes, and increased numbers of immigrants from malaria endemic countries who may be infective to mosquitoes but asymptomatic. We examine the factors known to influence malaria transmission and conclude that local transmission is possible but unlikely. The public health implications are that there should be systematic screening of immigrants from malaria endemic countries on arrival, and that the public health capacity to identify and respond to a malaria outbreak should be maintained.