Revascularization of theperiodontal tissues was studied after flap surgery. Modified Widman flap procedures were performed in four young Rhesus monkeys. All premolare and molars were involved. Experimental periods covered from 1 day to 90 days. The animals were sacrificed by exsanguination and perfused through the carotid arteries with a combined solution of equal parts of India ink and 10% buffered formalin solution. After fixation and decalcification, part of the blocks were processed to obtain cleared specimens following the Spalteholtz method. The remaining blocks were processed for routine histologic examination. The findings, mainly from the cleared specimens, showed that 1 day after surgery the supraperiosteal vessels in the flap demonstrated an overt hyperemic response. Patency of the vessels in the periodontal membrane and cancellous bone was evident; however, vessels were not depicted in the exposed cortical bone, nor in the clot. Vascular continuity apical to the surgical detachment was observed. In 3 to 4 days vascular proliferation within the organizing clot was observed and anastomosis between the gingiva and cancellous bone or periodontal membrane started to develop. At 7 days anastomoses were evident and vasodilation was present throughout the tissues. At 15 days and thereafter, vascular organization started to decrease, and the only hyperemic foci remaining were associated with areas of delayed bone remodeling, cementum remodeling or persistent marginal inflammation.