This experimental animal study compared the healing patterns between open and closed treatments of Achilles tendon tenotomies. Twenty-four male New Zealand rabbits underwent tenotomy of the left Achilles tendon and were randomized into two groups, treated with either open surgical repair or closed management. After the death of the animal, the retrieved tendons were submitted for biomechanical and histological testing. The total elongation of the open treatment group was 9.5+/-1.0 mm compared with 21.2+/-3.4 mm for the closed treatment group (P = 0.008), and the regain of stiffness was 67.4+/-2.0% and 48.9+/-5.3%, respectively (P = 0.132). Histological evaluation demonstrated similar healing patterns in both groups.