Improved Grapple( Player's Handbook v.3.5, p. 95)
[Fighter Bonus Feat, General]
You are skilled at grappling opponents.
Improved Unarmed Strike (PH) , DEX 13,
Scorpion's Grasp (Sa) ,
You do not provoke an attack of opportunity when you make a touch attack to start a grapple. You also gain a +4 bonus on all grapple checks, regardless of whether you started the grapple.
A fighter may select Improved Grapple as one of his fighter bonus feats (see page 38). A monk may select Improved Grapple as a bonus feat at 1st level, even if she does not meet the prerequisites.
Without this feat, you provoke an attack of opportunity when you make a touch attack to start a grapple.