Blast Shield - Blast Shield increases explosive resistance to the player. Blast Shield Pro grants the player resistance to both flashbangs and stun grenades. The perk and its pro version are similar to Flak Jacket and Tactical Mask from Call of Duty: Black Ops, respectively.
Blind Eye - The perk allows the player to be undetectable by air support and sentries. Its pro version makes the player's launchers lock-on quicker, and get extra bullet damage versus air support and sentries.
Assassin - Assassin is a Tier 2 perk set to appear in Call of Duty: Modern Warfare 3. The perk makes the player undetectable by UAV recon, Portable Radar, Thermal Scopes, and Heartbeat Sensors. Assassin Pro version makes the player immune to Counter-UAVs and EMPs, in addition to preventing the red crosshair being displayed when an enemy aims at the player.
Steady Aim - Same as in Black Ops and COD4
Dead Silence - You make no noise.
Recon - The core version makes explosive damage paint the target on the mini-map whilst the pro version makes bullet damage paint the target as well. So far, it is unknown if the perk paints the target to the entire team or just the player character.
Sleight of Hand - Decreases the reload time for all weapons by 50%. It has a new Pro effect, allowing the player to switch weapons faster, similar to Scout Pro from Call of Duty: Black Ops.
Extreme Conditioning - Same as in Black Ops and COD4...makes you run for longer periods of time..also, the pro version makes you climb over stuff quicker.
Scavenger - Unlocked at Level 39 in Multiplayer and its effect is unchanged from previous games.
Quickdraw - Quickdraw is a Tier 2 perk in Call of Duty: Modern Warfare 3. It makes the player aim down their sights faster, similarly to the Pro version of Sleight of Hand in Call of Duty: Modern Warfare 2 and Call of Duty: Black Ops. The Pro version allows the user to recover from equipment and grenade usage faster.
Hardline - Will make each Strike Chain require one less point. Hardline Pro will make every two assists count towards the player's Strike Chain in addition to making deathstreaks require one less death.
Overkill - Overkill allows players to carry two primary weapons, as in previous Call of Duty games, though the second weapon is incapable of accepting attachments. Overkill Pro allows the use of an attachment on the second primary or two if coupled with the attachments proficiency. This perk is featured in a default class giving the player a G36C and PP90M1. It is unlocked at level 47, the last of the Tier 2 perks.
Marksman - Marksman is a tier 3 perk in Call of Duty: Modern Warfare 3. The Marksman perk identifies enemy targets at a longer range by showing their player names at a greater distance. The pro version allows for longer hold breath period similar to Iron Lungs.
Stalker - Stalker is a Tier 3 perk set to appear in Call of Duty: Modern Warfare 3. Stalker gives the user faster movement speed while aiming down the sights. The pro version delays enemy Claymores similar to Scrambler Pro in Modern Warfare 2.
SitRep - SitRep functions in the same way as Modern Warfare 2, with enemy explosives flashing red. The pro effect magnifies the sounds of enemy footsteps, just as in Modern Warfare 2.