The stereocomplexation in three kinds of atactic poly (methyl methacrylate) (alpha-PMMA) films with different tacticities isolated from acetone, benzene, and chloroform solution was studied by Fourier transformation infrared (FTIR) and differential calorimetry scanning (DSC) techniques. Based on the results of infrared spectra, it could be deduced that stereocomplexes were formed in the films cast from acetone and benzene solutions with the increase in the population of trans-trans (rr) conformation of the backbone of i- and s-segments. It was assumed that the stereocomplexes formed by the interactions between i- and s-segments, possibly including intramolecular complexation. The stereocomplexation was also confirmed by the evidence of a endotherm with melt temperature over the range 180 degrees C to 200 degrees C, which was corresponded to the melting stereocomplex aggregates formed in the solutions and stabilized by the solvent molecules.