Oral disorders of small animals constitute a problem for veterinarians. Chronic oral infections are commonly seen in domestic cats. The objectives of this study were to characterise feline oral lesions, common feline dental problems, and especially the association of oral disease and systemic disease in cats. Two hundred and twenty cats referred over a period of 33 months to the Internal Medicine Department of our University with signs of oral disorders were included in this prospective study and were examined for the occurrence of the most commonly seen diseases. Infectious diseases which frequently cause ulcers and/or erosions within the mouth and on the tongue, constituted a significant proportion of the cases identified in this study. Feline Coronavirus (FCoV) infection was diagnosed in 36 cats (16%), Feline Calicivirus (FCV) in 17 cats (8%) and 16 cats (7%) had three viral infections (FCoV + Feline Immunodeficiency Virus (FIV) + Feline Leukemia Virus (FeLV)) at the same time. We conclude that oral disorders may be a sign of underlying systemic diseases in cats, especially in those diagnosed with feline viral infections. Other diagnosed diseases included immune-mediated disorders, eosinophilic granuloma complex, gastrointestinal system disorders, nutritional disorders, diabetes mellitus, hepatic disorders and chronic renal failure. Therefore, the first step in preventing oral disease in animals must be routine physical examination which includes a comprehensive oral exam.