  The coupling of the electroweak gauge bosons of the Standard Model (SM) to
leptons is flavour universal. Extensions of the SM do not necessarily have this
property. Rare decays of heavy flavour are suppressed in the SM and new
particles may give sizeable contributions to these processes, therefore, their
precise study allows for sensitive tests of lepton flavour universality. Of
particular interest are rare b to sll decays that are well accessible at the
LHCb experiment. Recent results from LHCb on lepton flavour universality in
rare b to sll decays are discussed.
