Most studies of the helminth fauna of the harbour porpoise Phocoena phocoena have focused on taxonomy, associated pathologies and surveys reporting prevalence and abundance of the parasite species. This study (1) characterizes the helminth fauna of the digestive tract of the harbour porpoise in Danish waters and (2) examines the influence of some factors structuring helminth communities within the host’s geographical range. Seventy digestive tracts (oesophagus, stomachs, duodenal ampulla and intestines) were analysed. We found 5 helminth species (Anisakis simplex, Hysterothylacium aduncum, Pholeter gastrophilus, Bolbosoma sp, and Diphyllobothrium sp.). Gastric ulcers associated with A. simplex were observed in 8 of the 28 porpoises infected with this parasite and gastric cysts produced by P. gastrophilus were observed in 2 of 70 porpoises analysed. No other pathologies were observed. The presence of H. aduncum and P. gastrophilus was the main difference between this study and a previous survey in the same area. Our data were compared with those of other analyses of helminth faunas from different harbour porpoise distribution areas. The geographical analysis suggested the presence of a strong local influence determining the helminth fauna, the cestode Diphyllobothrium stemmacephalum being the only species which could be considered as a specialist of the harbour porpoise. The intestinal helminth community of this host represents the most depauperate community recorded so far in a cetacean.