Forty two patients with functionally incapacitating 2+ or 3+ anterior instability underwent anterior cruciate ligament substitution using a meniscus (25 patients) or central third of the patellar tendon (17 patients). Subjective and objective evaluations were personally performed on all patients with an average followup of 15 months. Seventy-nine percent of the patients were objectively graded successful. Objective results were primarily based on the surgeon's technical ability to correct completely all components of anterior instability at the time of surgery. Subjective results were multifactorial and were correlated primarily with patient expectations, the presence or absence of continued buckling and the ability to return to recreational activities. The only observed difference between the two types of cruciate substitutions was the average loss of 6 degrees of flexion in the central third of the patellar tendon group. Both the patellar tendon and meniscus clinically appeared to be successful intraarticular cruciate substitutes which can predictably correct moderate to severe anterior instability of the knee in a high percentage of patients.