Pet birds are increasingly common patients in veterinary clinics. The occurrence of tumorous changes is preconditioned by an extended life span, improper diet, inappropriate living conditions and inbreeding in almost all bird species. Avian tumors found during physical examination or dissection include tumors of skin, oral cavity, sinus, liver, kidney, reproductive organs, bone, brain, vascular structures and connective tissue origin. The goal of this research was to make a pathohistological examination of archived tumorous changes, collected from pet birds in the Clinic of the Department of Poultry Diseases and the Department of Veterinary Pathology, to determine which type of tumor they belong to and to give insight into the most common tumors and their origin, as well as the age and type of birds in which the described tumors mostly occur. Through this research, tumors of different origin were observed in 23 samples. The largest number of samples were diagnosed as carcinoma, xanthoma and squamous cell carcinoma. The age range of birds whose ages were documented is quite wide, the youngest bird being 1.5 years old, and the oldest being 20 years old, but the vast majority of documented ages exceed five years, which makes the sample borderline geriatric. The species of bird from which the largest number of samples originates are budgerigars (Melopsittacus undulatus), whose genetic predisposition to renal carcinoma, xanthoma and squamous cell carcinoma was visible in the research results. Sexual predisposition has not been proven. Recurrences have been recorded in a few cases.