  Lambda flow in Ni+Ni collisions at SIS energies is studied in the
relativistic transport model (RVUU 1.0). It is found that for primordial
lambdas the flow is considerably weaker than proton flow. The inclusion of
final-state interactions, especially the propagation of lambdas in mean-field
potential, brings the lambda flow close to that of protons. An accurate
determination of lambda flow in heavy-ion experiments is shown to be very
useful for studying lambda properties in dense matter.
