Configuration of domain walls in undoped and Fe+3-doped lead zirconate titanate (PZT) ceramics at the morphotropic phase boundary has been investigated by the transmission electron microscopy. The distance between domain walls in undoped PZT is on the order of hundreds of nanometers and is drastically reduced to tens of nanometers by acceptor doping. The properties of doped and undoped samples are compared and discussed in terms of domain size, phase mixture, and presence of dopants. It is suggested that the small domain size cannot be a dominant effect in the enhancement of the properties in morphotropic PZT.