The unimpeded functioning of hospital Health Information Services (HIS) is essential for patient care, clinical governance, organisational performance measurement, funding and research. In an investigation of hospital Health Information Services' preparedness for internal disasters, all hospitals in the state of Victoria with the following characteristics were surveyed: they have a Health Information Service/ Department; there is a Manager of the Health Information Service/Department; and their inpatient capacity is greater than 80 beds. Fifty percent of the respondents have experienced an internal disaster within the past decade, the majority affecting the Health Information Service. The most commonly occurring internal disasters were computer system failure and floods. Two-thirds of the hospitals have internal disaster plans; the most frequently occurring scenarios provided for are computer system failure, power failure and fire. More large hospitals have established back-up systems than medium- and small-size hospitals. Fifty-three percent of hospitals have a recovery plan for internal disasters. Hospitals typically self-rate as having a 'medium' level of internal disaster preparedness. Overall, large hospitals are better prepared for internal disasters than medium and small hospitals, and preparation for disruption of computer systems and medical record services is relatively high on their agendas.