ObjectivesAnterior cruciate ligament rupture is a serious trauma with long-term consequences for the patient. Psychological and physiological factors may negatively affect patient recovery after anterior cruciate ligament reconstruction (ACLR), and development of kinesiophobia is possible. The aim of this study was to examine the presence of kinesiophobia and lower leg muscle strength recovery in both sexes after ACLR. Methods140 ACLR patients agreed to participate in the study. Kinesiophobia was assessed using the Tampa Scale of Kinesiophobia (TSK). The Knee injury and Osteoarthritis Outcome Score (KOOS), Oxford Knee Score (OKS) and Tegner activity score (TAS) were used for patient-related outcome measurements. In both legs quadriceps and hamstring muscle strength at 60˚/s and 180˚/s were measured with an isokinetic dynamometer. For dynamic balance and leg function, the Y-balance test and single-leg hop test were used. Results100 (71%) males and 40 (29%) females – mean age 32.5 (±8.3) – were examined 5.5 (±1.25) years after ACLR. 68/140 patients (48.6%) reported a TSK kinesiophobia score equal to or higher than 37 points: 54/100 (54%) males and 14/40 (35%) females (p=0.04). Patients with kinesiophobia had significantly lower KOOS values (p<0.001). In terms of the TAS no significant differences were found between those with or without kinesiophobia. Knee strength deficiency at 180°/sec and 60°/sec was significantly higher in the kinesiophobia group in knee extension in males (p=0.009) and knee flexion in females (p=0.001). Normalized body weight isokinetic average peak torque strength tests were significantly better in males compared to females in both groups (p < 0.001). ConclusionBoth sexes reported high rates of kinesiophobia, but males are at higher risk of developing kinesiophobia than females in the medium term after ACLR. Furthermore, patients with kinesiophobia have significantly lower total KOOS scores, and females were significantly weaker than males in knee flexion and extension according to normalized body weight muscle strength tests. Also, a longer time from injury to surgery increases the risk of kinesiophobia in females. Level of evidenceRetrospective case series study. Level IV Clinical Trial registrationTrial registration in ClinicalTrials.gov. Identifier: NCT05762809.