A stable at the Foxton Racecourse was engulfed in flames last night, the second fire there in three days.
On Friday a grandstand was badly damaged in a blaze which is believed to have been deliberately lit, a Fire Service spokesman said.
Last night's fire was already burning fiercely when firefighters arrived at about 11pm.
It took about 90 minutes to put it out, by which time the 50m stable had been badly damaged.
There were horses nearby but they were unharmed.
