The proportion of the world's population aged over 60 years is increasing. Therefore, there is a need to examine different methods of healthcare provision for this population. Medical day hospitals provide multidisciplinary health services to older people in one location. To examine the effectiveness of medical day hospitals for older people in preventing death, disability, institutionalisation and improving subjective health status. Our search included the Cochrane Effective Practice and Organisation of Care (EPOC) Group Register of Studies, CENTRAL (2013, Issue 7), MEDLINE via Ovid (1950-2013 ), EMBASE via Ovid (1947-2013) and CINAHL via EbscoHost (1980-2013). We also conducted cited reference searches, searched conference proceedings and trial registries, hand searched select journals, and contacted relevant authors and researchers to inquire about additional data. Randomised and quasi-randomised trials comparing medical day hospitals with alternative care for older people (mean/median > 60 years of age). Two authors independently assessed trial eligibility and risk of bias and extracted data from included trials. We used standard methodological procedures expected by the Cochrane Collaboration. Trials were sub-categorised as comprehensive care, domiciliary care or no comprehensive care. Sixteen trials (3689 participants) compared day hospitals with comprehensive care (five trials), domiciliary care (seven trials) or no comprehensive care (four trials). Overall there was low quality evidence from these trials for the following results.For the outcome of death, there was no strong evidence for or against day hospitals compared to other treatments overall (odds ratio (OR) 1.05; 95% CI 0.85 to 1.28; P = 0.66), or to comprehensive care (OR 1.26; 95% CI 0.87 to 1.82; P = 0.22), domiciliary care (OR 0.97; 95% CI 0.61 to 1.55; P = 0.89), or no comprehensive care (OR 0.88; 95% CI 0.63 to 1.22; P = 0.43).For the outcome of death or deterioration in activities of daily living (ADL), there was no strong evidence for day hospital attendance compared to other treatments (OR 1.07; 95% CI 0.76 to 1.49; P = 0.70), or to comprehensive care (OR 1.18; 95% CI 0.63 to 2.18; P = 0.61), domiciliary care (OR 1.41; 95% CI 0.82 to 2.42; P = 0.21) or no comprehensive care (OR 0.76; 95% CI 0.56 to 1.05; P = 0.09).For the outcome of death or poor outcome (institutional care, dependency, deterioration in physical function), there was no strong evidence for day hospitals compared to other treatments (OR 0.92; 95% CI 0.74 to 1.15; P = 0.49), or compared to comprehensive care (OR 1.05; 95% CI 0.79 to 1.40; P = 0.74) or domiciliary care (OR 1.08; 95% CI 0.67 to 1.74; P = 0.75). However, compared with no comprehensive care there was a difference in favour of day hospitals (OR 0.72; 95% CI 0.53 to 0.99; P = 0.04).For the outcome of death or institutional care, there was no strong evidence for day hospitals compared to other treatments overall (OR 0.85; 95% CI 0.63 to 1.14; P = 0.28), or to comprehensive care (OR 1.00; 95% CI 0.69 to 1.44; P = 0.99), domiciliary care (OR 1.05; 95% CI 0.57 to1.92; P = 0. 88) or no comprehensive care (OR 0.63; 95% CI 0.40 to 1.00; P = 0.05).For the outcome of deterioration in ADL, there was no strong evidence that day hospital attendance had a different effect than other treatments overall (OR 1.11; 95% CI 0.68 to 1.80; P = 0.67) or compared with comprehensive care (OR 1.21; 0.58 to 2.52; P = 0.61), or domiciliary care (OR 1.59; 95% CI 0.87 to 2.90; P = 0.13). However, day hospital patients showed a reduced odds of deterioration compared with those receiving no comprehensive care (OR 0.61; 95% CI 0.38 to 0.97; P = 0.04) and significant subgroup differences (P = 0.04).For the outcome of requiring institutional care, there was no strong evidence for day hospitals compared to other treatments (OR 0.84; 95% CI 0.58 to 1.21; P = 0.35), or to comprehensive care (OR 0.91; 95% CI 0.70 to 1.19; P = 0.49), domiciliary care (OR 1.49; 95% CI 0.53 to 4.25; P = 0.45), or no comprehensive care (OR 0.58; 95% CI 0.28 to 1.20; P = 0.14). There is low quality evidence that medical day hospitals appear effective compared to no comprehensive care for the combined outcome of death or poor outcome, and for deterioration in ADL. There is no clear evidence for other outcomes, or an advantage over other medical care provision.