Curvature Collineations for Gravitational pp Waves

Vacuum fields which admit a covariant constant vector are investigated in order to find ``curvature collineations,'' i.e., ${\mathrm{\pounds R}}_{\mathrm{klj}}^i\text{=0}$ . For all discussed types of pp waves it is shown that proper curvature collineations exist. We state the explicit form of these transformations.