Abstract.The initial-boundary value problem on the half-line R+ = (0, oo) for a system of barotropic viscous flow vt -ux = 0, ut + p(v)x = n{y^)x is investigated, where the pressure p(v) = v~y (7 > 1) for the specific volume v > 0. Note that the boundary value at x = 0 is given only for the velocity u, say u_, and that the initial data (vq,ilq)(x) have the constant states (u+,w+) at x = +00 with vq(x) > 0, v+ > 0. If < u+, then there is a unique i>_ such that (f+,u+) G (the 2-rarefaction curve) and hence there exists the 2-rarefaction wave uf)(x/t) connecting (u_,u_) with (v+,u+). Our assertion is that, if w_ < u+, then there exists a global solution (v,u)(t,x) in C°([0,00); Jcf1(R+)), which tends to the 2-rarefaction wave We consider the initial-boundary value problem on R+ = (0, oo) for a system of the barotropic viscous flow in the Lagrangean coordinate: