Incidental catches of harbour porpoises (Phocoena phocoena) were studied for the years 1986-89 by means of a salvage programme, an interview survey and a small scale reporting scheme. Data were obtained on 152 animals. Most were taken in large-mesh gillnets (mesh size 70-120mm) set for cod, turbot, lumpfish and plaice, throughout Danish waters. An estimated maximum take of 750 porpoises from a single harbour in northern Jutland (Hanstholm) indicates a considerable total take. The catch consists mainly of subadult animals. Behavioural reactions of the porpoises to presence of fishing gear are discussed and may indicate that the animals have a capability of learning to avoid net entanglement.