There are only few paper in Japan which reports the prevalence of pet keepers in the allergic population and also of the type of pets they keep. We made investigation on these points in 1337 allergic patients employing a questionnaire. Among 1337 patients, allergic conjunctivitis patients were found in 67, eczema patients in 118, allergic rhinitis patients in 368 and bronchial asthmatic patients in 1043. These number contained those who overlapped in symptoms. Approximately 43% of allergy patients are currently keeping the pet at present while 11.2% of the patient had kept the pet in the past. There were two peaks in the age when they began to keep a pet, 6 to 12 and 30 to 40 years of age. Trend in the past decade showed that both the dog and cat bred in foreign countries were increasing. About 80% of patients who own the foreign bred dogs keep them indoor. This ratio is increasing gradually. Another conspicuous change is the sharp increase in those who keep hamsters which occupied 20% of all the pet keeper in 1997. Percentages of the patient who recognizes the aggravation of their symptoms in eye, nose, skin and also as asthma often pet keeping is a about 10%. One out of 4 patients who keep the pet has a family member with rhinitis and/or asthma. We concluded that too many of the allergic patients keep the pet against their benefit and they must be informed that the pet could be the cause of allergy symptoms.