Rats with arteriosclerosis induced by a hypercholesterolic diet were over a period of six weeks submitted to occlusal disorders. Hyperfunc-tion was established by a high filling in the first mandibular molar, and hypofunction was achieved by removing the antagonist tooth. Histological examination revealed an increased number of inflammatory cells in the gingiva surrounding the disordered tooth, both in the experimental ana the control animals. During the six weeks of occlusal disorder, however, a marked increase in the number of inflammatory cells, as well as epithelial proliferation and deepening of the gingival pocket in the gingival sulcus area, was observed in one-third of the experimental animals. This frequency was statistically higher than that found in the controls at the p<0.05 level. In all the experimental animals the gingival connective tissue showed degenerative changes. The apposition of alveolar bone had diminished and osteoclastic resorption had increased. In the control animals the periodontal effects of the occlusal disorders were slight.