The man has been quarantined at the private Nyaho Clinic in the capital, Accra, health officials say.
The virus has so far killed more than 460 people since it broke out in Guinea in February and spread to neighboring Liberia and Sierra Leone.
It is the world’s deadliest outbreak to date, and there is no cure for Ebola.
The U.S. embassy in Accra said it had been informed that a U.S. citizen was being tested but would not give any more details, Reuters news agency reports.
The American was believed to have visited Guinea and Sierra Leone in recent weeks.
Ghana’s health ministry said it had put in place “precautionary measures,” and urged people to stay calm.
Staff at the clinic had also been quarantined and provided with protective clothing, it added in a statement.
Symptoms of the virus include high fever, bleeding and central nervous-system damageThe fatality rate can reach 90 percent and the incubation period is two to 21 days.
There is no vaccine or cure. Supportive care such as rehydrating patients who have diarrhea and vomiting can help in recovery. Fruit bats are considered to be the natural host of the virus, health officials report.
The clinic is awaiting the results of blood tests to see whether the patient, whom the ministry also did not identify, really contracted Ebola, the statement said.
“We will like to assure the general public that we have everything under control,” Tony Goodman, the health ministry’s public relations officer, said.
Read more at bbc.com