Transversity at Hermes

Spin physics is the main focus of the HERMES physics program. Over the last five years measurements have been performed with polarised lepton beam and polarised or unpolarised nuclear targets. In this contribution results on single-spin asymmetries in semi-inclusive hadron production from longitudinally polarized targets are presented. These results are compared with theoretical calculations which relate the azimuthal dependence of the observed asymmetries to the transversity structure function h₁(x).