A reciprocating laboratory shaker (10) includes a platform (12) driven by a motor (62) which is constrained to move in a reciprocating fashion by a pair of flexible bands (30, 32) located on opposite sides of the platform (12). A frame (24), which preferably supports the drive motor (62), includes a pair of upright supports (28) which are attached to a pair of wide, but thin, flexible plastic bands (30, 32) at least at two locations. Each of the two flexible bands (30, 32) includes a pair of rollers (34, 36, 38, 40) attached to the inside surface (50) of the bands (30, 32). The laboratory platform (12) is attached to the remaining outside face (52) of the bands and is driven by the drive motor (62) having an appropriate crank mechanism (54). The two flexible bands (30, 32) constrain the motion of the platform (12) to substantially a single direction, x, while preventing it from moving in either the y or z directions.