Primary repair of anterior cruciate ligament is superior to late reconstruction procedures for two reasons; objective stability is more easily restored due to intact secondary restraints not subjected to chronic stress, and the quality of the joint is superior with greater chance of intact menisci and normal articular cartilage not yet damaged through recurrent subluxation. We present the result of thirty-eight kness in thirty-seven patients who had been treated with primary repair of augmented repair for acute ACL rupture from March, 1984 to August, 1990. Twenty-one knees were treated with primary repair and seventeen knees augmented repair. At an average 33 months follow up, the results obtained were as follows: 1. The patients were 23 males and 14 females with an average age of 27.1 years. 2. Twenty four knees were injuried during athletic endeavors, 9 knees by automobile accident, and 5 knees by landing from height. In 18 knees anterior cruciate ligament was ruptured at the proximal attachment, in 17 knees at the midsubstance tear and in 3 at the near distal attachment. 3. The average interval from injury to operation was 7.5 days (ranged from 1 to 14 days). 4. The results were evaluated by Hospital for Special Surgery knee rating scale (modified by Marshall) at an average 33 months (range from 13 months to 7 years and 6 months) follow-up study. 16 (76%) out of 21 knees treated with primary repair were rated as good or excellent. 12 (86%) out of 14 knees treated with augmented repair were rated as good or excellent. As the result of this study, acutely torn anterior cruciate ligaments appear to be successfully treated with primary repair or augmented repair according to torn site and shape of ligaments.