Furunculosis appears from time to time in salmonids in different rivers. It was noted in sea tout from the Dunajec River in 1923 and 1924. In 2007 and 2008, it was noted in sea trout and salmon from Pomeranian rivers, where from 80 to 2,400 sea trout spawners were caught. The degree of infection ranged widely from 0.00% in the Łeba to 74.7% in the Słupia and Rega rivers. In 2007, of the 1,381 sea trout weighing 1949.5 kg caught in the Słupia River, 1031 fish weighing 1,664 kg were cleared for utilization. The most diseased fish were observed in the Słupia and Rega rivers. The number of salmon caught in 2007 and 2008 was lower than that of sea trout and ranged from 2 to 65 individuals from the various rivers. The percentage of infected fish ranged from 8.3% (Słupia) to 58.3% (Rega). Funuculosis was noted more frequently in males than females, as well as in more salmon than in sea trout. Bacteriological assays indicated the presence of Aeromonas hydrophila Complex, Aeromonas sorbia, Pseudomonas flurescens, Streptococus mutans, Streptococus sp. Internal organ bleeding was also noted. In the Vistula, Drwęca, Łeba, and Łupawa rivers and in hatcheries rearing spawners of both salmon and sea trout, no symptoms of furunculosis were noted.