We　present　transmission　electron　microscopy　(TEM)　observations　of　stacking　faults　(SFs)　and　their　interactions　with　pyramidal　dislocations,　in　plastically　deformed　polycrystalline　pure　magnesium.　We　have　observed　well-defined　fringes　its　well　as　streaking　in　diffraction　patterns,　typical　of　SFs.　The　basal　SFs　are　decorated　by　a　large　number　of　dark　speckles,　which　are　created　by　the　interaction　with　pyramidal　dislocations　that　have　both　＜　c　＞　and　＜　a　＞　components　as　revealed　by　our　contrast　analysis.　The　SFs　do　not　appear　to　result　from　the　splitting　of　unit　dislocations,　as　the　SFs　are　relatively　wide　and　no　dislocation　nodes　were　observed.　By　tilting　the　specimen　systematically　inside　TEM,　the　SFs　and　the　associated　dislocations　in　Mg　are　found　to　exhibit　a　rich　variety　of　features　in　terms　of　their　morphology　and　diffraction　contrast.　(C)　2009　Acta　Materialia　Inc.　Published　by　Elsevier　Ltd.　All　rights　reserved.