The S-matrix of the relativistic theory of charged scalar particles in
teracting via the Chern-Simons field is shown to be formally equivalen
t to the S-matrix of scalar QED in 2 + 1 dimensions in which the Feynm
an diagrams with external photon lines are excluded and the propagator
s of the Chern-Simons particles are substituted instead of the photon
propagators. It is shown that the non-relativistic limit of the scatte
ring amplitude of two anyons is also finite independently of the prese
nce of the contact interaction, unlike the non-relativistic theory. It
is found that for a certain value of the contact interaction, the sca
ttering amplitude coincides with that of Aharonov-Bohm scattering in t
he same approximation.