Abstract: Disclosed is a lift mechanism which is particularly adapted for use in a dental chair. The lift mechanism comprises a base plate, a support attached to and extending vertically from the base plate, the support having two planar side surfaces parallel to each other, and a diagonal strut attached near the upper portion of the support and to the base plate. The mechanism further comprises a carriage structure extending horizontally from and traveling on the support and having two parallel horizontal arms extending in one direction from the support. The carriage structure also includes two horizontal rollers between the arms, the rollers contacting the parallel side surfaces of the support. The rollers are of length approximately equal to the width of the contacted side surface and the roller nearest to the portion of the arms extending from the support is located lower in the carriage structure than the other roller.