Melt spinning of 50/50 hollow segmented-pie bicomponent fibers, each containing a pair of either poly(lactic acid) (PLA) and poly(butylene succinate) (PBS) or PLA and polypropylene (PP), was conducted to investigate effects of constituent polymers on arrangement and properties of the obtained fibers. PLA/PBS fibers exhibited flat interfaces between PLA and PBS segments, while PLA/PP fibers exhibited curved interfaces having concave-shaped PLA segments and convex-shaped PP segments. The curvature at interfaces was due to the molten low-viscosity PLA encapsulating the high-viscosity PP. The results showed that fiber splitting was complex, and its mechanism depended not only on the properties of each polymer constituent but also interactions between them. PLA/PP fibers exhibited the tendency of fiber splitting due to the incompatibility between PLA and PP as well as an imbalance force at the interface. In PLA/PBS fibers, the fiber splitting was not observed. The balance force of flat interface between PLA and PBS could contribute to the reduction of interfacial tension. In addition, small domain size in a range of 3-5 A mu m could favor compatibility between the PLA and PBS segments. Observations from this study suggested a possibility of employing segmented-pie configuration as an alternative approach for developing PLA/PBS fibers of high PBS content without phase separation.