Aromatic block copolyamides with well-controlled molecular weights (MWs) and narrow polydispersities (PDIs) were successfully prepared by the condensative chain polymerization of 3-[4-(N-octylamino)benzoyl]benzoxazoline-2-thione (1) and 3-[4-(N-1,1,1,2,2,3,3,4,4,5,5,6,6-tridecafluorooetylamino)benzoyl]benzox azoline-2-thione (2). The formation of the block copolymers was confirmed by GPC, DSC, and NMR analyses. The thin film formed on mica was analyzed using atomic force microscopy (AFM), and the results indicated the existence of phase segregation.