The Saudi man was admitted to hospital in the Red Sea city of Jeddah after showing symptoms of haemorrhagic fever upon his return from Sierra Leone.
The patient, in his 40s, is in critical condition and has symptoms "similar to that of Ebola infection."
Ebola-like symptoms include fever, vomiting, severe headaches and muscular pain and, in the final stages, profuse bleeding.
The UN World Health Organisation said Monday that at least 887 people have died from Ebola since the beginning of the year, after the virus spread across Guinea, Liberia and Sierra Leone.
In April, Saudi Arabia announced a ban on visas for Muslims in the three West African nations wishing to perform the pilgrimage to the Muslim holy sites there.