The 19-year-old man was set upon by four men and a woman in Glasgow Central at around 8.45pm.
He was attacked by the gang at the low-level entrance of the station, near Argyle Street.
It is understood he was punched in the face before the gang ran off in the direction of nearby Hope Street.
The victim made his way to the high-level station concourse before being taken by ambulance to Glasgow Royal Infirmary.
Police said the teenager may have a suffered a broken nose in the attack.
The female suspect is described as being in her early 20s, about 5ft 4in with long dark hair.
She was wearing black-and-white striped clothing. One of the men was described as 6ft, in his mid 20s, with a tanned complexion.
The other man was around 5ft 7in and wearing a green jacket.
No descriptions of the other two men are available.
A spokesman for British Transport Police, said: "At around 8.45pm, a 19-year-old man from the South Side of Glasgow was assaulted by a group of around five people at the low-level entrance of Glasgow Central station.
"Those believed to be involved were last seen on CCTV leaving the station via the Argyle Street exit and heading towards Hope Street.
"The victim made his way to the high-level station concourse before being taken by ambulance to Glasgow Royal Infirmary.
"He may have a broken nose.
"This appears to be an unprovoked attack and British Transport inquiries are ongoing."
Anyone with any information is asked to contact British Transport Police on 0800 40 50 40.