Following anterior cruciate ligament reconstruction (ACL) patients have altered movement patterns in the reconstructed knee during walking. There is limited information about these alterations over an extended period of time. This study was designed to present a longitudinal analysis of gait patterns following ACL reconstruction surgery. Assessments of level walking were undertaken in 16 participants at a mean 10 months (initial assessment) and again at 3 years (follow-up assessment) after ACL reconstruction surgery. Kinematic and kinetic variables were analysed using a two factor (time, limb) repeated measures ANOVA. Kinematic data showed that patients were able to achieve greater extension about the reconstructed knee at follow-up than at initial assessment. The reconstructed knee was significantly less internally rotated than the contralateral knee at the initial assessment but not at follow-up. Kinetic data showed a significant increase in the external knee extension moment for the reconstructed limb over time. There were also significant increases in the external knee adduction moment for both limbs at the follow-up assessment. The external knee adduction moment was however smaller in the reconstructed knee than the contralateral knee at both assessments. The results indicate that gait variables do change over time and that measurement at a single time point may not reflect the long term outcome of ACL reconstruction surgery. The changes were however small and may not be clinically relevant. However, the consistently reduced external knee adduction moment seen about the reconstructed knee in this study may suggest that factors other than joint moments influence degenerative change over time.