Introduction: Although a well-known advantage of thecementless fixation technique is that it prevents bone cementimplantation syndrome, with lower perioperative mortality,the risk factors associated with dislocation after cementlessbipolar hemiarthroplasty (BHA) have not yet been sufficientlyinvestigated. This study aimed to investigate the incidenceof dislocation following cementless BHA of the hip in elderlypatients with displaced femoral neck fractures. The related riskfactors are also examined.Methods: In this nested case-control study, patients who hadundergone BHA for femoral neck fracture at a single tertiaryreferral center were retrospectively reviewed. Three controlpatients from the cohort who had not experienced dislocationwere selected for each patient who developed dislocationfollowing BHA. Clinical and radiographic outcome measureswere then assessed to determine the risk factors for dislocationfollowing BHA.Results: Of the 103 patients available for the analyses inthe current study, 23 patients (12 females, 11 males) withdislocation were selected as the study group and 70 patients(33 females, 37 males) without dislocation were included inthe control group. Univariate analyses revealed significantdifferences between the two groups in terms of numberof postoperative surgical site infections, dementia, centeredgeangle, and femoral offset. Two independent risk factorsassociated with dislocation, namely, infection and dementia,were identified during multivariate model analysis.Conclusion: Patients with postoperative surgical site infectionor dementia are at greater risk for developing dislocation aftercementless BHA.