Background: Vital signs monitoring is an old hospital practice for patient safety but evaluation of its effectiveness is not widespread. We aimed to identify strategies to improve intermittent or continuous vital signs monitoring in general wards; and their effectiveness in preventing adverse events on general hospital wards. Methods: Publications searched between 1980 and June 2014 in five databases. Main outcome measures were in-hospital death, cardiac arrest, intensive care unit (ICU) transfers, length of stay, identification of physiological deterioration and activation of rapid response systems. Results: Twenty-two studies assessing the effect of continuous (9) or intermittent monitoring (13) and reporting outcomes on 203,407 patients in-hospital wards across 13 countries were included in this review. Both monitoring practices led to early identification of patient deterioration, increased rapid response activations and improvements in timeliness or completeness of vital signs documentation. Innovative intermittent monitoring approaches are associated with modest reduction in in-hospital mortality over intermittent vital signs monitoring in ‘usual care’. However, there was no evidence of significant reduction in ICU transfers or other adverse events with either intermittent or continuous monitoring. Conclusions: This review of heterogeneous monitoring approaches found no conclusive confirmation of improvements in prevention of cardiac arrest, reduction in length of hospital stay, or prevention of other neurological or cardiovascular adverse events. The evidence found to date is insufficient to recommend continuous vital signs monitoring in general wards as routine practice. Future evaluations of effectiveness need to be undertaken with more rigorous methods and homogeneous outcome measurements.