The 21-year-old was attacked in Weston Park at around 10.50pm on Monday, January 23.,
She woke up on the ground afterwards with no recollection or memory of what had happened.
The woman was unable to provide a description of her attacker, but detectives are analysing CCTV footage and have spoken to people in the area at the time. She is being supported by specialist officers, with South Yorkshire Police treating the incident as a 'priority'.
Audrey Leadley, Head of Student Support and Guidance at the University of Sheffield, said: "We are extremely concerned about a serious incident that took place in Weston Park on Monday, January 23.
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"The University is supporting South Yorkshire Police in its investigation in every way we can."The safety and welfare of our students, staff and local community is paramount.
"The University is offering support to everyone affected by this incident and we continue to highlight important safety advice to all our students and staff.”
Police patrols are being carried out around the unversity campus following the attack.
The university's Women's Officer, Serena Cavasin, has published safety advice online following the attack.
She said: "The University of Sheffield and Sheffield Students’ Union take student safety very seriously. It is very important to us that you feel safe when you’re out and about in Sheffield, regardless of gender.
"If you’re studying late on campus, you can use the Student Union’s 'Safe Taxi Scheme' to get home safely. If you're a female student, you can also use the women's mini bus.
"During the exam period, the women’s mini bus runs some extra services.
"If you do have to walk home, make sure you walk in a group and stick to well-lit areas as much as possible. You can also pick up a personal safety alarm from the Student Advice Centre.
"The police have increased the number of patrols in the area and may be seen in and around campus. They will be liaising closely with university security services to ensure the best service possible.
"If you have experienced an incident on or near campus which has made you feel unsafe, you can report this to university security services."
Anyone with information about the attack should call South Yorkshire Police on 101.