British media reports said the woman was thought to have travelled abroad recently, but the Northampton General Hospital spokeswoman could not immediately confirm that.
"A patient with a suspected case of Ebola was admitted to Northampton General Hospital this evening," the hospital said in a statement.
It said tests have shown the patient does not have malaria, and added that while "Ebola is considered unlikely, testing is being done as a precaution."
"We are confident that all appropriate actions are being taken to protect the public's health and ensure there is no risk to patients or staff," it said.
A British nurse diagnosed with Ebola last month is being treated in hospital in London, where doctors said on Monday she was no longer in critical condition.
Pauline Cafferkey, a 39-year-old nurse who normally works at a health centre in Scotland, became the first person to be diagnosed with the disease in Britain after contracting it in Sierra Leone where she was volunteering at an Ebola clinic.
The World Health Organization (WHO) said on Wednesday the global death toll from the Ebola epidemic had reached 8,429 out of 21,296 reported cases.