Abstract: An apparatus withdraws blood from a vein or artery and collects it in a collection vessel. The collection vessel includes blood inlet means and air outlet means communicating with the ambient air. The blood inlet means is adapted to accept an intravenous needle having one end ensheathed in a flexible sleeve. The blood inlet means is adapted to engage the flexible sleeve and form a seal therewith. An adaptor holds the intravenous device and collection vessel together.