Officials believe that the oversight may have resulted in the man being infected with the HIV virus.
Sweden's Board of Health and Welfare (Socialstyrelsen) has issued a sharp criticism against the hospital, according to the newspaper Göteborgs Posten.
The two patients, one hospitalized with HIV and the other with severe head injuries, were housed in the same room at the hospital.
Both were to be given injections, but when the nurse went to give the patient with head injuries his injection she accidentally took the syringe which had been used earlier on the HIV patient.
The syringe, which was placed near the patient with head injuries, wasn't marked with the HIV patient's name or personal identity number (personnummer).
Upon realizing the mistake, the hospital elected to treat the patient with head injuries as an HIV patient.
However, the man died of his injuries before the hospital could confirm whether or not he'd in fact contracted HIV.
The Board wrote in its report there is a high probability the man was infected with HIV and is demanding that the hospital improve its routines.
This is the second time in recent weeks that the Board has reprimanded Sahlgrenska.
Two weeks ago, health authorities criticized the hospital because a woman was infected with HIV by her husband after he'd received faulty test results showing he was free from the virus.