The use of solvent annealing to control the microdomain orientation and long-range ordering in poly(isoprene-b-D,L-lactide) thin films was investigated using scanning force microscopy and grazing incidence small angle X-ray scattering (GISAXS). Benzene and chloroform were used as annealing solvents. Both were found to improve the long-range order in the films. Additionally, at high concentrations of chloroform in the film, a perpendicular orientation of cylinders was observed where the solvent was able to mediate interfacial interactions sufficiently to prevent a preferential segregation of one of the blocks to the surface. In situ GISAXS measurements made during solvent swelling and evaporation allowed an examination of the film morphology over a wide range of solvent concentrations providing it efficient route to optimize conditions for morphology control by solvent annealing (c) 2005 Elsevier Ltd. All rights reserved.