  Light extra U(1) gauge bosons, so called hidden photons, which reside in a
hidden sector have attracted much attention since they are a well motivated
feature of many scenarios beyond the Standard Model and furthermore could
mediate the interaction with hidden sector dark matter. We review limits on
hidden photons from past electron beam dump experiments including two new
limits from such experiments at KEK and Orsay. In addition, we study the
possibility of having dark matter in the hidden sector. A simple toy model and
different supersymmetric realisations are shown to provide viable dark matter
candidates in the hidden sector that are in agreement with recent direct
detection limits.
