Main goal of this paper is to study the description of monogenic functions by their geometric mapping properties. At first monogenic functions are studied as general quasi-conformal mappings. Moreover, dilatations and distortions of these mappings are estimated in terms of the hypercomplex derivative. Then pointwise estimates from below and from above are given by using a generalized Bohr’s theorem and a Borel-Carathéodory theorem for monogenic functions. Finally it will be shown that mono- genic functions can be defined as mappings which map infinitesimal balls to special ellipsoids.