Abstract: Ecologists are always perplexed with the question: why do some species become invasive but others not. A number of studies from different aspects have been conducted including the comparison among different species. However, satisfactory explanations for invasion success remain elusive, and the effects of taxonomical relatedness on the comparative studies have been neglected, making the results incomparable. Comparing the invasive species with their congeners or comparing exotic species of varying invasiveness can partially avoid the bias due to taxonomical relatedness and enhance the credibility of the results. Congeneric comparisons have been widely used in the study of invasive species from the families of Asteraceae, Gra-mineae and Pinaceae, approaching some important issues that are stressed in the invasion biology of these taxa: biological traits, habitat invasibility, invasion prediction and control. Here we review the applications of comparative studies of congeners in invasion ecology, with an emphasis on their importance and recent pro-gress.