"Test results will probably be received sometime this evening. At this stage it is just a suspicion, other illnesses are entirely possible," a statement from regional health authorities in Uppsala, about 70 kilometres (45 miles) north of Stockholm, said.
"The patient is being treated at the infectious diseases clinic at Uppsala University Hospital and is isolated."
No other details about the patient or how he or she may have contracted Ebola were disclosed.
The patient was first admitted to hospital in the nearby town of Enkoping.
The emergency room of that hospital has now been closed, and staff who came in contact with the patient are being cared for, the statement said.
An Ebola outbreak ravaging eastern areas of the Democratic Republic of Congo has claimed several hundred lives. It is the 10th such outbreak in the Congo since the disease was first detected there in 1976.