Police in Renfrewshire are appealing for information following the incident, which happened between 7pm and 9.30pm, in a wooded area behind Dykebar Hospital off of Grahamston Road.
The teenager was found by a passing motorist in nearby Hurlet Road.
The two male suspects are described as white Scottish, early 20s, and were wearing dark clothing.
One man was around 5ft 9ins tall, and the other was around 6ft.
Detective Inspector Colin MacRitchie said: “This was a terrifying ordeal for the victim and we are doing everything we can to provide her with all the necessary support she requires at this time.
“Officers have been searching the woods and Grahamston Road area, checking CCTV and carrying out door-to-door enquiries in the surrounding area since this was reported.
“I am appealing to anyone in the area at the time who may have seen anything suspicious, or men matching this description, to come forward.
“Do you live nearby and have CCTV? Were you driving and have a dash-cam? If so, please check back and see if there is any footage that could assist our investigation.
“It does not matter if you think your information is small or minor – it could be just the detail we are looking for to help build a bigger picture of the circumstances.
Anyone with information in connection is asked to contact police on 101, quoting reference number 4478 of 20 March. Alternatively, if you wish to remain anonymous, you can pass on information to the independent charity Crimestoppers on 0800 555 111 which is 100% confidential.