Hemorrhagic pneumonia is an acute and fatal disease of farmed mink caused by Pseudomonas aeruginosa. The pathogenesis of this disease has not yet been resolved. Mink are the only animals known to be susceptible to acute, contagious and fatal lung infections caused by P. aeruginosa. To elucidate the pathogenesis of the disease, an infectious dose-response trial was performed on adult mink and mink kits both in the season for hemorrhagic pneumonia (November) as well as out of season (July). It proved difficult to infect mink via the intra-nasal route. Only 4 out of 60 infected mink developed clinical disease and were euthanized, all of them in November, indicating that predisposing factors in the mink itself might be crucial for disease development. We were able to culture P. aeruginosa from the nasal cavity of the clinically healthy experimental mink eight days after inoculation showing that the mink can carry P. aeruginosa on their nasal mucosa without developing disease. It was, however, not possible to culture P. aeruginosa from the nasal cavity of clinically healthy mink obtained from farms in November indicating that the organism is not a normal part of the nasal mucosal flora of mink.