There has been a heavy police presence near Rose Lane in the centre of town since a man was found with serious injuries in the early hours of Monday morning.
A Police Scotland spokeswoman said: “Police in Fife are investigating after a 26-year-old man was found with serious injuries in St Andrews.
“The incident occurred in Rose Lane at around 2am on Sunday. The man was taken to Ninewells Hospital, Dundee, for treatment.
“Enquiries into how the man sustained his injuries are ongoing.
“Anyone with information is asked to contact Police Scotland on 101.”