General formulae allowing the evaluation of the form factors of cyclic
block copolymers are established and graphs for cyclic copolymers of
the form (A-B)(N) are shown. When N is large, the linear and the cycli
c copolymer have the same behaviour. It is possible to extend at large
angle an analytical expression given for linear polymers. This allows
to show that, in the study of transesterification by small-angle neut
ron scattering, one can neglect the effect of cycles.