Isotactic (it-) and syndiotactic (st-) uniform poly(methyl methacrylate)s (PMMAs) with hydroxyl end groups were isolated by supercritical fluid chromatography (SFC) and reacted with benzene-1, 3, 5-tricarbonyl trichloride. Two types of uniform three-arm star-PMMAs with different stereoregular arms, [it/it/st]- and [it/st/st]-3-star-PMMAs, that is, ‘stereostar PMMAs’, were isolated by SFC from the product mixture (According to IUPAC nomenclature for nonlinear polymers, star PMMA with three arms is named 3-star-PMMA. In this paper, the stereoregularity of the three arms is designated as [it/it/st], for example, and thus, the polymer is named [it/it/st]-3-star-PMMA. By analogy to ‘stereoblock’ PMMAs, these star PMMAs are termed ‘stereostar’ PMMAs). The formation of stereocomplexes by these stereostar PMMAs was examined in acetone. Although both stereostar PMMAs formed intramolecular stereocomplexes, the [it/st/st]-3-star-PMMA formed two types of intramolecular stereocomplexes with different hydrodynamic volumes because of the different compositions of the it- and st-PMMA arms involved in the stereocomplexes.