A 35-year-old man is being questioned on suspicion of attempted murder after a 20-year-old man was taken to hospital with multiple stab wounds.
Sussex Police were called to Holly Court in Bognor Regis shortly before midnight on New Year's Eve following reports of a fight between two men.
The injured man was admitted to St Richard's Hospital in Chichester. His injuries were not life-threatening.
Police are appealing for anyone with information to come forward.