In this paper, we introduce and study the intuitionistic fuzzy prime (semi-prime) ${Gamma}$-ideals of ${Gamma}$-LA-semigroups and some interesting properties are investigated. The main result of the paper is: if $A={langle}{mu}_A,{gamma}_A{ angle}$ is an IFS in ${Gamma}$-LA-semigroup S, then $A={langle}{mu}_A,{gamma}_A{ angle}$ is an intuitionistic fuzzy prime (semi-prime) ${Gamma}$-ideal of S if and only if for any $s,t{in}[0,1]$, the sets $U({mu}_A,s)={x{in}S:{mu}_A(x){geq}s}$ and $L({gamma}_A,t)={x{in}S:{gamma}_A(x){leq}t}$ are prime (semi-prime) ${Gamma}$-ideals of S.