Two patients -- of the same age and from the same nursing home -- were misidentified in hospital, according to reports.
Slovenian health authorities apologised on Thursday after an old man was cremated by a different family under another man's name.
Officials say it is "totally unacceptable" that the name tags of two patients were confused.
"Someone cremated his father yesterday only to find out the next day that he was alive, while another family realised it was their relative who was actually dead," Health Minister Danijel Bešič Loredan told a news conference.
The two wheelchair-bound men were the same age, from the same nursing home and had both been taken to the hospital in Celje for health reasons in the same ambulance. One of the patients was suffering from advanced dementia.
Two days later, one of them died and the wrong family was informed. After the obligatory forensic check, they organised the cremation of his body and a funeral.
The mistake was only discovered when the other man returned to the nursing home after recovering in hospital. Staff then realised that he had the wrong identity tag on his wrist.
"In the age of digitisation in the 21st century, this is totally unacceptable," Bešič Loredan said in a statement.
An investigation into the matter has been launched and the hospital's management is expected to resign.