Objectives: To compare the antero-posterior knee laxity and compliance in athletes and control subjects. Design: Cross-sectional comparison of different groups. Setting: Laboratory based study. Participants: sixty-four athletes and 25 control subjects aged 14–20. Athletes were trained for at least 2 years at a minimum of 6h per week in their respective sports events, namely, basketball (n=27), running (n=20), swimming (n=17). Main outcome measure: Antero-posterior laxity, stiffness and rate of change in stiffness of the dominant knee at 100N of anterior drawer force measured with a KT-2000 knee arthrometer. Results: Data were tested with multivariate analysis of variance with α=0·05. Results revealed significant differences between groups in knee laxity (P=0·035) and the change in stiffness (P=0·034). There is a strong trend of difference between groups in stiffness (P=0·067). Post-hoc linear contrasts revealed that the swimming and basketball groups had significantly less laxity and higher stiffness than the control group (P<0·05). Conclusions: These findings suggest that sports training may improve the strength of soft tissues in the knee joint, and different kinetic demands of the sport events may result in unique response of the joint structures.