The health system in RWR is not the usual one most might be used to from many other shooters as you don't "take damage" in the traditional sense.
In fact, every bullet can kill at any moment. You don't have a health bar or any other indication that you've been hit for that matter (until you're dead, that is).
Every weapon has a different kill probability which is around 50% for assault rifles but can be up to 100% for some precise weapons like sniper rifles, e.g. if those hit you, you are dead.
However, there is an armor type item in-game that comes a bit closer to a health-point system - a vest (to be more specific, the Vest Type II is used in this example).
It gives you the ability to survive 3 lethal shots, each shot bringing its own consequences and damaging the vest. These vests can be bought at the Armory. Vests can also be worn by some AI soldiers - Vest Type II(hey, give them some fun too!) and by Elite soldiers(Officers) - Vest Type III. Vest Type III can be obtained by knifing enemy Elite soldiers(Officers) and the stabbed enemy will drop a vest down to 60% or can be found in a secret crates(unscathed). A vest icon is shown to the right of the grenade slot. You can recognize a vest-carrier by a darker vest model around his torso like on the picture below:
Soldier without vest
Soldier with vest
In the table below those 3 stages of the vest status are listed below:
|The vest is pristine, no shots have been LETHAL toward you yet. In the case that you do get hit by a LETHAL bullet, the vest will absorb the bullet as if nothing had happened. Of course, this does damage it, and if you get shot by a lethal bullet again, there will be consequences.
|This vest has absorbed ONE lethal bullet, and is slightly damaged, so the NEXT TIME you get hit by a LETHAL bullet, it will only protect you enough so that you escape unharmed, but as a consequence you will be stunned in pain on the ground for a few seconds, unable to move and very vulnerable to more shots, but if you can get up then you are alive if you manage to get away without being shot again. However, the vest will be damaged even more, and with that comes even more consequences.
This vest is torn up, and will only be enough to protect against ONE more LETHAL bullet. Even so, the vest will be so damaged that it can only stop you dying and instead inflict you with a wound. The vest will be completely destroyed.
While wounded, you are permanently prone, and can only move very slowly. You can call for help by clicking the button you normally use to shoot (default is left mouse button). You can also still use your radio while wounded; and remember, every reinforcement call has at least one medic in it.