A secondary economic impact analysis of an invasion of Australia by the Old World screwworm fly (SWF) Chrysomya bezziana Villeneuve on the economy of the State of Queensland was undertaken with the use of a dynamic bio-economic model developed by the Queensland Department of Primary Industries (QDPI). The analysis was based on the scenario of the fly entering Australia through Brisbane and Cairns (two of the busiest ports in Queensland), detected 13 weeks after entry and completely eradicated in the fifth year of the invasion using sterile insect technique (SIT) after completion of a SIT factory in the middle of the third year of invasion. The 1985/1986 revised 29-sector input-ouput table compiled by the Queensland Department of Treasury in 1993 was used to evaluate the impact of the potential invasion. The results indicated that an eradicated SWF invasion would have a small negative impact overall on the economy of Queensland as measured by the reduction of gross state product (GSP), income and employment. The impact would generally be minimal in the first year, would become increasingly worse from the second year and would peak in the third year of the invasion. The negative impact on the economy would be substantially reduced in the fourth year, with full recovery of the economy taking place in the fifth year as SWF eradication was completed. The expected reduction in outputs of beef cattle, sheep and dairy cattle sectors and the closely related food manufacturing (meat abattoirs) and wool-processing sectors would have a negative effect on the production of other sectors of the economy. These downward effects would be partially offset by the positive effects derived from the construction of a 250 million files per week SIT factory in Queensland to eradicate the fly, and the release of funds from the federal government and other states and territories (under a cost-sharing agreement for the control and eradication of exotic pests in Australia) for the implementation of an eradication campaign in Queensland.