Originally Posted by
FriendlySkies
You'll be fine. I only use the first initial of my middle name, even though my ID has my full name. Never had a problem with TSA or customs in England or the U.S.
By customs you mean immigration, right?
It is certainly possible that a different / shortened name (compared with passport) used on an international ticket could cause some issues. Much more likely if the last name is spelled differently, but still possible with a first name.