Third-year student Ashraful Islam has been admitted to Savar's Enam Medical College and Hospital.
Assistant Proctor Shikdar Mohammad Julkarnaine said the assault took place on Sunday evening in front of the new building of Arts Faculty.
He said Ashraf had a brawl with second-year physics student Kawsar Ahmed Ovi as the latter had been ragging a first-year student of the department several days ago.
"Kawsar and several of his accomplices beat up Ashraf with sticks and rods finding him alone in the evening," Julkarnine said.
Proctor Tapan Kumar said he had asked Ashraf's friends to file a written complaint.
"We'll take actions against the accused based on the complaint," he said.
"He has been shifted to Enam Medical College and Hospital as he sustained severe injuries," said the university's assistant medical officer Dr Touhid Hasan Shah Chowdhury.
Students claim Kawsar is a member of ruling Awami League's student front Bangladesh Chhatra League's Shaheed Rafiq Jabbar Hall unit.
BCL's JU unit chief Mahmudur Rahman Jony claimed the assault was a result of the department's in-fighting.