Comprehensive geriatric assessment (CGA) is a multi-dimensional, multi-disciplinary diagnostic and therapeutic process used to identify medical, mental, and functional problems in older adults with frailty, enabling a coordinated treatment plan. This review updates a previous Cochrane review, assessing the effectiveness and cost-effectiveness of CGA for older adults admitted to hospital. The review included 29 randomized trials involving 13,766 participants across nine countries. CGA increased the likelihood of older adults being alive and living at home at 3 to 12 months follow-up (RR 1.06, 95% CI 1.01 to 1.10; high-certainty evidence). It decreased the likelihood of admission to a nursing home (RR 0.80, 95% CI 0.72 to 0.89; high-certainty evidence) and had little effect on mortality (RR 1.00, 95% CI 0.93 to 1.07; high-certainty evidence) or dependence (RR 0.97, 95% CI 0.89 to 1.04; high-certainty evidence). CGA had little effect on cognitive function (SMD ranged from -0.22 to 0.35; low-certainty evidence). The average length of hospital stay was longer in the CGA group (1.63 to 40.7 days) compared to the usual care group (1.8 to 42.8 days). Healthcare costs in the CGA group were on average GBP 234 higher than in the usual care group (low-certainty evidence). CGA may lead to a slight increase in quality-adjusted life years (QALYs) of 0.012 (95% CI -0.024 to 0.048) at GBP 19,802 per QALY gained, a slight increase in life years (LYs) of 0.037 (95% CI 0.001 to 0.073) at GBP 6305 per LY gained, and a slight increase in life years living at home (LYLAH) of 0.019 (95% CI -0.019 to 0.155) at GBP 12,568 per LYLAH gained. The probability that CGA would be cost-effective at a GBP 20,000 ceiling ratio for QALY, LY, and LYLAH was 0.50, 0.89, and 0.47, respectively. Older patients are more likely to be alive and in their own homes at follow-up if they received CGAComprehensive geriatric assessment (CGA) is a multi-dimensional, multi-disciplinary diagnostic and therapeutic process used to identify medical, mental, and functional problems in older adults with frailty, enabling a coordinated treatment plan. This review updates a previous Cochrane review, assessing the effectiveness and cost-effectiveness of CGA for older adults admitted to hospital. The review included 29 randomized trials involving 13,766 participants across nine countries. CGA increased the likelihood of older adults being alive and living at home at 3 to 12 months follow-up (RR 1.06, 95% CI 1.01 to 1.10; high-certainty evidence). It decreased the likelihood of admission to a nursing home (RR 0.80, 95% CI 0.72 to 0.89; high-certainty evidence) and had little effect on mortality (RR 1.00, 95% CI 0.93 to 1.07; high-certainty evidence) or dependence (RR 0.97, 95% CI 0.89 to 1.04; high-certainty evidence). CGA had little effect on cognitive function (SMD ranged from -0.22 to 0.35; low-certainty evidence). The average length of hospital stay was longer in the CGA group (1.63 to 40.7 days) compared to the usual care group (1.8 to 42.8 days). Healthcare costs in the CGA group were on average GBP 234 higher than in the usual care group (low-certainty evidence). CGA may lead to a slight increase in quality-adjusted life years (QALYs) of 0.012 (95% CI -0.024 to 0.048) at GBP 19,802 per QALY gained, a slight increase in life years (LYs) of 0.037 (95% CI 0.001 to 0.073) at GBP 6305 per LY gained, and a slight increase in life years living at home (LYLAH) of 0.019 (95% CI -0.019 to 0.155) at GBP 12,568 per LYLAH gained. The probability that CGA would be cost-effective at a GBP 20,000 ceiling ratio for QALY, LY, and LYLAH was 0.50, 0.89, and 0.47, respectively. Older patients are more likely to be alive and in their own homes at follow-up if they received CGA