OBJECTIVE To investigate the adequacy of hospital disaster preparedness in the Osaka, Japan area. METHODS Questionnaires were constructed to elicit information from hospital administrators, pharmacists, and safety personnel about self-sufficiency in electrical, gas, water, food, and medical supplies in the event of a disaster. Questionnaires were mailed to 553 hospitals. RESULTS A total of 265 were completed and returned (Recovery rate; 48%). Of the respondents, 16% of hospitals that returned the completed surveys had an external disaster plan, 93% did not have back-up plans to accept casualties during a disaster if all beds were occupied, 8% had drugs and 6% had medical supplies stockpiled for disasters. In 78% of hospitals, independent electric power generating plants had been installed. However, despite a high proportion of power-plant equipment available, 57% of hospitals responding estimated that emergency power generation would not exceed six hours due to a shortage of reserve fuel. Of the hospitals responding, 71% had reserve water supply, 15% of hospitals responding had stockpiles of food for emergency use, and 83% reported that it would be impossible to provide meals for patients and staff with no main gas supply. CONCLUSIONS No hospitals fulfilled the criteria for adequate disaster preparedness based on the categories queried. Areas of greatest concern requiring improvement were: 1) lack of an external disaster plan; and 2) self-sufficiency in back-up energy, water, and food supply. It is recommended that hospitals in Japan be required to develop plans for emergency operations in case of an external disaster. This should be linked with hospital accreditation as is done for internal disaster plans.