Police, who have not yet released the name of the motorcyclist, said the man in his 50s died ten days after the crash in Upper Minety, near Malmesbury.
A spokesman said: "The collision happened on Flisteridge Road at around 4.45pm on Friday 18 September when a motorcyclist collided with a tractor.
"The motorcyclist suffered serious injuries and was taken to Southmead Hospital in Bristol.
"Sadly, he died of his injuries on Saturday.
"His family are aware and our thoughts are with them at this very sad time."
An investigation into the collision is ongoing and we would urge anyone with information to call Wiltshire Police’s collision investigation unit on 101, quoting reference 54200094260.