In order to determine the characteristics of medical institutions which patients with 30 intractable diseases visited, we analyzed data of a nationwide survey conducted by the Epidemiology of Intractable Diseases Research Committee in 1989. Each of 47 prefectural governments in Japan reported information of all patients with 30 intractable diseases who received financial aid for the diseases between April 1988 and March 1989. Information collected about each patient consisted of identification numbers, which included the disease code, sex, age, the code of the municipality where the patient lived, the medical institution which treated the patient, etc. Out of 173,637 patients whose information was reported by prefectural governments, we used data of 159,910 patients whose medical institutions were reported completely. The results can be summarized as follow: 1) Of the 159,910 patients, 8.6 percent visited medical institutions outside of the prefectures where the patients lived. Many patients living in prefectures located close to large cities, such as Tokyo, visited medical institutions in large cities. 2) The proportion of patients who visited hospitals of medical schools was 27.9 percent. 3) Patients who were affected by diseases causing physical disabilities such as SMON and malignant rheumatoid arthritis tended to visit medical institutions located in their neighborhoods and were treated in small hospitals or clinics. Old patients had the same tendency as patients with such diseases. 4) Although the number of patients receiving aid in 1988, whose data we analyzed in the current study, was larger than that in 1984, the proportion of patients visiting medical institutions outside of the prefecture where the patients lived, and the proportion of patients visiting hospitals of medical schools were nearly equal to those in 1984.