The impact of biological invasions should be considered from ecological and economic perspective. To understand the influence of the invader, both its range and abundance should be known. Even if the range of invaders is well-known, the problem of assessing their abundance still occurs very often. In this study we report the results of an assessment of the area covered by stands of alien Solidago species in Silesia (Central Europe, south-western Poland, area ca. 30 000 km²), and estimated costs of the invaded areas recultivation. The results of field survey show that the stands of invasive Solidago species cover an area of about 130 000 hectares in S-W Poland, which is ca. 4.5% of the total area of the studied region. It was also found that the cadastral data and Corine land cover maps underestimate the area of fallowed agricultural lands. The cost of removing stands of invasive Solidago species in S-W Poland ranges from 123.24 to 266.17 million PLN, depending on the method. The method that balances reasonable costs, low environmental impact and efficiency of grassland establishment costs 180.7 million PLN for S-W Poland.