A computer system at a Cambridge hospital is experiencing some problems because of the fire at the Buncefield oil depot in Hertfordshire.
A company providing some IT services to Addenbrooke's Hospital was based at the industrial park near the depot and was destroyed in the fire.
A hospital spokeswoman said the system was used for patient information such as admissions and discharges.
A manual system is in place so patients should turn up as already instructed.
The spokeswoman said it would take a week to get the computer system up and running again.
No medical services provided by the hospital have been affected.
"We would really like to encourage patients only to call us if they have an urgent need, for example to cancel or postpone an appointment for this week or next," the spokeswoman said.