Arthrofibrosis represents a severe complication of trauma and reconstructive joint surgery because of generalized connective tissue proliferation resulting in painful joint stiffness. It often appears stereotypical in terms of its clinical and pathologic features, comprising excess deposition of extracellular matrix proteins such as collagen type I, III, and VI and proliferation of fibroblasts. However, trauma and surgery around joints does not always lead to fibrosis, suggesting a genetic predisposition. For a number of autoimmune diseases, strong associations have been described. The objective of the study was to investigate whether an association of HLA (human leukocyte antigen) with primary arthrofibrosis exists.Retrospective cohort study.Seventeen patients with primary arthrofibrosis after autologous anterior cruciate ligament (ACL) reconstruction were identified and clinically reviewed. Blood samples were taken, and DNA was isolated by column extraction method. DNA samples were typed for the loci HLA-A, -B, -C, -DRB1, and -DQB1. Results were compared with the frequencies of allelic groups as determined for the caucasoid population.HLA-Cw*07 was significantly less often found in the patient group than in the general population (P =.022). The opposite effect was seen for Cw*08, which was found in 17.6% of the patient group but only in 3.8% of the reference group (P =.045). A significant difference was also seen for DQB1*06, because 23.5% of the patients but 48.6% of the reference group possessed an allelic variant of this group (P =.048). However, according to the relatively small number of patients, a statistical bias cannot be excluded.A possible link may exist between arthrofibrosis and HLA-Cw*07- and DQB1*06-negative as well as Cw*08-positive individuals. Further investigation is necesessary to confirm or vitiate the possible association.Level IV.