In NRL, HIA stands for Head Injury Assessment. It is a series of checks used in professional and Test rugby to determine whether or not a player is suffering from concussion and may or may not return to the field of play. The HIA protocol is a three-stage process introduced by World Rugby for professional medical teams to assist with the identification, diagnosis, and management of head impact events with the potential for a concussion. The three stages of the HIA protocol are:

• Stage 1 – game day, off-field assessment using the HIA1 Form
• Stage 2 – post-game, same-day assessment using HIA2 Form
• Stage 3 – 36-48 hour post-injury assessment using HIA3 Form

In NRL, clubs are given a free interchange if a player leaves the field for an HIA. The NRL uses a similar system to World Rugby, with players having to complete a series of tests before the regular season kicks off, so if they leave the field injured with concussion, the medical staff can gauge the level of impairment from the knock.