The study aimed at the analysis of prevalence frequency and localisation of tumours in domestic animals. The research material comprised 4,212 tumours developed in dogs, cats, horses, and exotic animals, isolated during surgery, autopsy or biopsy, performed for the purpose of histopathological diagnosis. The most numerous group involved canine tumours, including 3,585 cases (85.1%), followed by tumours in cats (532 cases, 12.6%), ferrets (34 cases, 0.81%), rats (19 cases, 0.45%), horses (15 cases, 0.36%), and rabbits (14 cases, 0.33%). A significant increase in incidence of tumours was noted, as compared to studies performed in the same region of Poland in 1957-1995 and 2000-2004 or in 2005-2008. This was particularly evident in exotic animals, in which 80 cases (1.9%) were detected in 2009-2011 but only 20 cases (1.2%) in 2005-2008. The most frequent localisation of neoplasia involved the skin, subcutaneous tissue, and mammary gland.