The objective of this study was to collect epidemiological data on neoplasms in pet ferrets in Japan. A questionnaire to collect information was made available to Japanese veterinary practitioners through the web site of the Japanese Society of Exotic Pet Medicine. Completed questionnaires were returned from 29 practices, and 945 neoplasms met the criteria for inclusion in the study. Neoplasms were found in every organ system except the respiratory system; the endocrine (418; 44.2%), integumentary (196; 20.7%) and hemolymphatic (184; 19.5%) systems were most commonly affected. The most common tumor types were pancreatic islet cell tumor (211: 22.3%), adrenal gland tumor (207; 21.9%) and lymphoma (152; 16.1%). The age of the affected ferrets ranged from less than 3 months to more than 7 years of age. Tumor incidence was highest in ferrets between 4 and 6 years of age. No sex predilection was found. These results were similar to those recently published in North America. Most Japanese pet ferrets are imported from North America, and their husbandry including diets is similar to that in North America, which may explain the similar tendencies in the incidence of neoplasms in this study and those of findings in North America.