The purposes of this investigation were to compare outcomes of anterior cruciate ligament (ACL) reconstruction between patients with generalized joint laxity and those without it and to investigate the effect of generalized joint laxity on outcomes of ACL reconstruction from 2 to 8 years postoperatively. We retrospectively reviewed 163 patients who had undergone unilateral ACL reconstruction from January 2001 to December 2008. Patients were divided into 2 groups according to presence or absence of generalized joint laxity. The proportions of patients with meniscectomy, graft rupture, and contralateral ACL rupture were compared. Rupture rates were compared with Kaplan-Meier analysis. The Lachman test, pivot-shift test, and anterior translation measured with the KT-2000 arthrometer were evaluated. The Lysholm knee score and International Knee Documentation Committee (IKDC) subjective score were compared. The IKDC objective grade and radiographic grade were also evaluated. Follow-up assessments were performed at 2, 5, and 8 years postoperatively. The proportions of meniscectomy, graft rupture, and contralateral ACL rupture in patients with generalized joint laxity were higher than in patients without generalized joint laxity during the whole evaluation period. However, differences in proportions and cumulative rupture rates did not reach significance (p > 0.05). Patients with generalized joint laxity had less stability and poorer functional outcomes at the 8-year follow-up compared with patients without generalized joint laxity. With regard to the Lachman test and anterior translation, poorer results were shown in patients with generalized joint laxity than in patients without generalized joint laxity during the whole evaluation period. The results of pivot-shift testing differed significantly at 5 years (p = 0.002) and 8 years (p = 0.007). Patients with generalized joint laxity also had worse Lysholm knee scores and IKDC subjective scores during the whole evaluation period; these differences may not be clinically important. Comparisons between serial outcomes measured at 2, 5, and 8-year follow-ups within each patient group showed that anterior translation (p = 0.002), Lysholm knee score (p = 0.014), and IKDC subjective score (p = 0.002) deteriorated over time, although the values at 8 years were similar to those at 5 years, in patients with generalized joint laxity. Generalized joint laxity as an inherent physiologic characteristic of patients was related to a significant adverse effect on stability and functional outcomes of ACL reconstruction for patients followed for 2 to 8 years. Generalized joint laxity should be considered a risk factor for poor outcomes after ACL reconstruction. Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.