Abstract: A laboratory jack having a scissors-type jack assembly connected to upper and lower platforms includes guide members and thrust bearings or rollers, which provide improved stability across a longer stroke than previous laboratory jacks. One laboratory jack includes upper and lower tiers of scissor assemblies comprised of scissor arms and guide rods disposed between the ends of each of the upper and lower scissor assemblies. The guide rods are carried by cross-brace members that are connected to and extend between opposing portions of the scissor assemblies, and the guide rods slide through a through bore in at least one of the cross-brace members. The scissor assemblies include rollers at the interface between laterally shifting ends of the scissor arms and an adjacent platform.