The coastguard helicopter carried out a search yesterday lunchtime (February 13) following reports of a person seen face down in the water.
The person was spotted near the Brighton Sailing Club, Kings Road Arches just after 2pm.
The man was pulled from the water by beach patrol officers and taken to hospital by ambulance.
Police say his condition is unknown at this time.
Police, coastguard teams, the coastguard helicopter, Shoreham RNLI lifeboat carried out a search of the sea and shoreline to check for any further casualties. They were stood down after no one else was found.