This article presents some preliminary results from the research on the impact of three wind farms in Flanders (Belgium) on birds. The collision numbers varied from 0 to 125 birds per wind turbine per year. The mean number in 2002 was 24, 35 and 18 birds per wind turbine per year. It is important to know that the mentioned numbers of victims have to be regarded as a strict minimum. The number of collisions on the three studied locations seems to be dependent on the number of passing birds, and in less degree with the size of the wind turbine.Most of the victims were abundant present birds like gulls, ducks and pigeons but we also found rarer species as Grey Heron, Peregrine Falcon, Redshank, Common Tern, Little Tern and Stonechat. The calculated collision chance at rotor height varied between 1 on 12.000 and 1 on 600 passing birds. Most resting or foraging waterfowl species held a distance of 150-300 m from the wind turbines. At one location in the port of Zeebrugge we saw that most gulls and terns, flying between the breeding colonies and feeding areas at sea, crossed the line of wind turbines in a normal way. Therefore, in contrast to the situation with seasonal migration of many species and local migration of waterfowl, during the breeding season the wind turbine line was no barrier for these birds. However, this study also demonstrates that area’s with many local migrations of birds can have a relatively high number of collision victims. The impact on seasonal migrating birds is still unclear, and more research is urgently needed certainly concerning the collision factor.