In this paper we describe the invasion history of benthic crustacean species that have recently invaded the Estonian coastal sea. Physical characteristics of their habitat and communities associated with the invasive species were explored. The crustaceans Gammarus tigrinus, Chelicorophium curvispinum, Pontogammarus robustoides, and Paramysis intermedia are the most recent newcomers in the Estonian coastal sea. All these species have formed permanent populations and more aggressive species have likely caused significant shifts in the community structure and functioning. Besides the true invasive species, some native amphipod species have significantly expanded their range in the Baltic Sea. This group consists of rare or previously not spotted benthic invertebrate species in the northern Baltic Sea range such as Echinogammarus stoerensis, Calliopius laeviusculus, and Melita palmata.