OBJECTIVE: To examine the effect of high-intensity progressive resistance strength training (HIPRST) on strength, function, mood, quality of life, and adverse events compared with other intensities in older adults. DATA SOURCES: Online databases were searched from their inception to July 2012. STUDY SELECTION: Randomized controlled trials of HIPRST of the lower limb compared with other intensities of progressive resistance strength training (PRST) in older adults (mean age ≥ 65y) were identified. DATA EXTRACTION: Two reviewers independently completed quality assessment using the Physiotherapy Evidence Database (PEDro) scale and data extraction using a prepared checklist. DATA SYNTHESIS: Twenty-one trials were included. Study quality was fair to moderate (PEDro scale range, 3-7). Studies had small sample sizes (18-84), and participants were generally healthy. Meta-analyses revealed HIPRST improved lower-limb strength greater than moderate- and low-intensity PRST (standardized mean difference [SMD]=.79; 95% confidence interval [CI], .40 to 1.17 and SMD=.83; 95% CI, -.02 to 1.68, respectively). Studies where groups performed equivalent training volumes resulted in similar improvements in leg strength, regardless of training intensity. Similar improvements were found across intensities for functional performance and disability. The effect of intensity of PRST on mood was inconsistent across studies. Adverse events were poorly reported, however, no correlation was found between training intensity and severity of adverse events. CONCLUSIONS: HIPRST improves lower-limb strength more than lesser training intensities, although it may not be required to improve functional performance. Training volume is also an important variable. HIPRST appears to be a safe mode of exercise in older adults. Further research into its effects on older adults with chronic health conditions across the care continuum is required.