Fire crews were called to Northampton General Hospital after a fire was reported outside the labour ward building.
The flames were spotted in a bin store near to the maternity day unit and the outpatient unit.
A fire service spokeswoman said three crews were sent to the site at 11.40pm last night and discovered rubbish well alight. They eventually left the scene at 1.36am after making the area safe.
NGH said, although staff were preparing to evacuate, nobody was forced to leave either building and nobody was hurt as a result of the fire.
The flames also caused damage to two external doors, which are to be replaced.
A spokesman said: “This was a minor incident in terms of impact on patients and staff but it could have been much worse.
“We will be doing our own investigation to find out how the fire started.”