The 16-year-old boys were arrested in connection with an attack on a 19-year-old man in Leconfield Road, Lancing, in the early hours of Sunday morning.
The victim was attacked at around 2.45am by a group of people, some of whom are believed to have used weapons, near the junction with Tower Road.
PC Victoria Tidman said: “This was a serious assault on a young man, who appears to have been set upon by a large group of people as he walked home.”
The victim was taken to Worthing Hospital were he received treatment for a broken arm and serious facial injuries.
Police believe others may have been involved and are appealing for witnesses to call 0845 6070999 quoting serial 0216 of 6/03.