The paper deals with a quaternionic Beltrami-type equation, which is a very
natural generalization of the complex Beltranni equation to higher dimensi
ons. Special attention is paid to the systematic use of the embedding of th
e set of quaternions H into C-2 and tho corresponding application of matrix
singular integral operators. The proof of the existence of local homeomorp
hic solutions is based on a necessary and sufficient criterion, which relat
es the Jacobian determinant of a mapping from R-4 into R-4 to the quaternio
nic derivative of a monogenic function.