A ring R of the kind described
by the title is called a right q-ring and is characterized by the property that each of
its right ideals is quasi-injective as a right R-module. The principal results of this
paper are Theorem 6, which describes how an arbitrary right q-ring is constructed
from division rings, local rings, and right q-rings with no primitive idempotent, and
Theorem 5 which shows that a right q-ring cannot have an infinite set of orthogonal
noncentral idempotents.