  We study Lie algebra prederivations. A Lie algebra admitting a non-singular
prederivation is nilpotent. We classify filiform Lie algebras admitting a
non-singular prederivation but no non-singular derivation. We prove that any
4-step nilpotent Lie algebra admits a non-singular prederivation. The results
can be applied to construct affine structures on Lie algebras.
