The present investigation studies the changes that occur in periodontal supporting tissues of lower canine and premolar of marmosets (Callithrix jacchus), due to experimental modification of occlusal relationships in the region of the molar. For our purposes an extracoronal arch wire of 0.7 mm diameter was fixed into occlusal perforations of the upper third premolar and first molar, on both sides. Eight male marmosets weighing from 250 to 350 grams were used. After each experimental time interval of 7, 14, 21 and 28 days two animals were sacrificed. The results clearly showed areas of tension with stretch periodontal fibers in the distal region of the canine and areas of pressue with osseous and redicular resorption in the mesial region of the first premolar. The tissue changes may be considered to result from transmission of abnormal forces through the proximal contacts of teeth associated with displacements and minor modifications in their occlusal relationships. Similar changes may occur in a tooth distant from the teeth exposed to primary excessive occlusal forces.