Colonization of test panels by micro- and macrofouling organisms was studied at two selected sites in the Warnow estuary. The stations differed substantially in terms of their physical and chemical parameters. Station 1 was situated in the Warnemünde marina and can be considered typical of the outer port area. The site selected for Station 2 was a floating shipyard dock about 10 km upstream. The water there had lower salinity and higher nutrient loads than at Station 1. The short,14-day-long periods of exposure were intended primarily to yield information concerning the rate and variability of colonization. In addition, long-term exposure panels were deployed for the entire period of the experiment at both stations. Species diversity was lower in both the micro- and macrofouling communities at Station 2. Settlement of diatoms and ciliates proceeded throughout the whole season, its intensity being higher in spring at both stations. Domination of ciliates was more pronounced at Station 2 than at Station 1, diatoms being more abundant at Station 1. The macrofouling community at Station 1 was dominated by Balanus improvisus, Laomedea loveni, Electra crustulenta, Mytilus edulis, and Fabricia sabella, while the community at Station 2 was dominated by Balanus improvisus, Cordylophora caspia, and Nais elinguis.