Hip fractures are a major healthcare problem, presenting a huge challenge and burden to individuals and healthcare systems. The number of hip fractures globally is rising rapidly. The majority of hip fractures are treated surgically. This review evaluates evidence for types of arthroplasty: hemiarthroplasties (HAs), which replace part of the hip joint; and total hip arthroplasties (THAs), which replace all of it./r/nTo determine the effects of different designs, articulations, and fixation techniques of arthroplasties for treating hip fractures in adults./r/nWe searched CENTRAL, MEDLINE, Embase, seven other databases and one trials register in July 2020./r/nWe included randomised controlled trials (RCTs) and quasi-RCTs comparing different arthroplasties for treating fragility intracapsular hip fractures in older adults. We included THAs and HAs inserted with or without cement, and comparisons between different articulations, sizes, and types of prostheses. We excluded studies of people with specific pathologies other than osteoporosis and with hip fractures resulting from high-energy trauma./r/nWe used standard methodological procedures expected by Cochrane. We collected data for seven outcomes: activities of daily living, functional status, health-related quality of life, mobility (all early: within four months of surgery), early mortality and at 12 months after surgery, delirium, and unplanned return to theatre at the end of follow-up./r/nWe included 58 studies (50 RCTs, 8 quasi-RCTs) with 10,654 participants with 10,662 fractures. All studies reported intracapsular fractures, except one study of extracapsular fractures. The mean age of participants in the studies ranged from 63 years to 87 years, and 71% were women. We report here the findings of three comparisons that represent the most substantial body of evidence in the review. Other comparisons were also reported, but with many fewer participants. All studies had unclear risks of bias in at least one domain and were at high risk of detection bias. We downgraded the certainty of many outcomes for imprecision, and for risks of bias where sensitivity analysis indicated that bias sometimes influenced the size or direction of the effect estimate. HA: cemented versus uncemented (17 studies, 3644 participants) There was moderate-certainty evidence of a benefit with cemented HA consistent with clinically small to large differences in health-related quality of life (HRQoL) (standardised mean difference (SMD) 0.20, 95% CI 0.07 to 0.34; 3 studies, 1122 participants), and reduction in the risk of mortality at 12 months (RR 0.86, 95% CI 0.78 to 0.96; 15 studies, 3727 participants). We found moderate-certainty evidence of little or no difference in performance of activities of daily living (ADL) (SMD -0.03, 95% CI -0.21 to 0.16; 4 studies, 1275 participants), and independent mobility (RR 1.04, 95% CI 0.95 to 1.14; 3 studies, 980 participants). We found low-certainty evidence of little or no difference in delirium (RR 1.06, 95% CI 0.55 to 2.06; 2 studies, 800 participants), early mortality (RR 0.95, 95% CI 0.80 to 1.13; 12 studies, 3136 participants) or unplanned return to theatre (RR 0.70, 95% CI 0.45 to 1.10; 6 studies, 2336 participants). For functional status, there was very low-certainty evidence showing no clinically important differences. The risks of most adverse events were similar. However, cemented HAs led to less periprosthetic fractures intraoperatively (RR 0.20, 95% CI 0.08 to 0.46; 7 studies, 1669 participants) and postoperatively (RR 0.29, 95% CI 0.14 to 0.57; 6 studies, 2819 participants), but had a higher risk of pulmonary embolus (RR 3.56, 95% CI 1.26 to 10.11, 6 studies, 2499 participants). Bipolar HA versus unipolar HA (13 studies, 1499 participants) We found low-certainty evidence of little or no difference between bipolar and unipolar HAs in early mortality (RR 0.94, 95% CI 0.54 to 1.64; 4 studies, 573 participants) and 12-month mortality (RR 1.17, 95% CI 0.89 to 1.53; 8 studies, 839 participants). We are unsure of the effect for delirium, HRQoL, and unplanned return to theatre, which all indicated little or no difference between articulation, because the certainty of the evidence was very low. No studies reported on early ADL, functional status and mobility. The overall risk of adverse events was similar. The absolute risk of dislocation was low (approximately 1.6%) and there was no evidence of any difference between treatments. THA versus HA (17 studies, 3232 participants) The difference in the risk of mortality at 12 months was consistent with clinically relevant benefits and harms (RR 1.00, 95% CI 0.83 to 1.22; 11 studies, 2667 participants; moderate-certainty evidence). There was no evidence of a difference in unplanned return to theatre, but this effect estimate includes clinically relevant benefits of THA (RR 0.63, 95% CI 0.37 to 1.07, favours THA; 10 studies, 2594 participants; low-certainty evidence). We found low-certainty evidence of little or no difference between THA and HA in delirium (RR 1.41, 95% CI 0.60 to 3.33; 2 studies, 357 participants), and mobility (MD -0.40, 95% CI -0.96 to 0.16, favours THA; 1 study, 83 participants). We are unsure of the effect for early functional status, ADL, HRQoL, and mortality, which indicated little or no difference between interventions, because the certainty of the evidence was very low. The overall risks of adverse events were similar. There was an increased risk of dislocation with THA (RR 1.96, 95% CI 1.17 to 3.27; 12 studies, 2719 participants) and no evidence of a difference in deep infection./r/nFor people undergoing HA for intracapsular hip fracture, it is likely that a cemented prosthesis will yield an improved global outcome, particularly in terms of HRQoL and mortality. There is no evidence to suggest a bipolar HA is superior to a unipolar prosthesis. Any benefit of THA compared with hemiarthroplasty is likely to be small and not clinically appreciable. We encourage researchers to focus on alternative implants in current clinical practice, such as dual-mobility bearings, for which there is limited available evidence.