Анотация: LYMPHOMAS are one of the most common systemic neoplasms affecting companion animals, accounting for 7 to 24 per cent of all neoplasms and 83 per cent of haematopoietic tumours. Lymphomas are generally responsive to multiagent chemotherapy and, although patients are rarely cured, they can enjoy a good quality of life during remission. Although survival times and treatment regimens have not improved significantly over the past 20 years, some progress has been made recently with regard to chemotherapy protocols for lymphomas and their diagnosis and monitoring. This article describes the classification of lymphomas commonly seen in dogs and outlines the approach to diagnosis. An article in the next issue will discuss the treatment options for canine lymphoma