An in-vitro model that simulates tooth eruption was devised to determine the possible role of periodontal ligament fibroblasts (PLF) in providing a major force for eruption. The model consisted of agarose-coated wells in multiwell tissue-culture plates to which wire mesh was attached at the rim and a slice of demineralized root was attached to the floor. When the wells were filled with a collagen lattice containing PLF, the lattice contracted and elevated the root slice. The root slice in models that were unattached at the rim was not elevated. Cultures without cells did not contract and root slices were not elevated. Elevation was inhibited by cytochalasin D and Colcemid. Histologically, cultures that had elevated showed orientated cells and collagen fibres. The results suggest that PLF may be capable of generating forces that are sufficient to produce tooth eruption.