  We investigate Lie symmetries of the self-dual Yang-Mills equations in
four-dimensional Euclidean space (SDYM). The first prolongation of the symmetry
generating vector fields is written down, and its action on SDYM computed.
Determining equations are then obtained and solved completely. Lie symmetries
of SDYM in Euclidean space are in exact correspondence with symmetries of the
full Yang-Mills equations in Minkowski space.
