Firefighters responded to reports of smoke coming from Greene King in Bury St Edmunds on Friday night.
Three fire crews from the town were sent to the brewery in Westgate Street at around 11.30pm.
It turned out to be a false alarm.
A spokeswoman for Greene King said: “The steam from the brewery, which can appear to look like smoke, is created when Greene King boils the wort to create bitterness in its beers. On a cold evening, the steam can look denser and is more noticeable.”