Background: Rapid Response Teams (RRTs) assess patients during early phases of deterioration to reduce patient morbidity and mortality. Objectives: This study aimed to evaluate the ability of earlier medical intervention by a RRT prompted by clinical instability in patients to reduce the incidence of and mortality from unexpected cardiac arrest at our hospital. Patients and Methods: A nonrandomized, population-based study before 2008 and after 2010 introduction of the Rapid Response Teams in a 300 bed private hospital. All patients were admitted to the hospital in 2008 (n = 25348) and 2010 (n = 28024). RRT (One doctor, one senior intensive care nurse and one staff nurse) attended to clinically unstable patients immediately with resuscitation drugs, fluid, and equipment. Response was activated by the bedside nurse or doctor according to predefined criteria. Main outcome measures were incidence and outcome of unexpected cardiac arrest. Results: The incidence of unexpected cardiac arrest was 17 per 1000 hospital admissions (431 cases) in 2008 (before RRT intervention) and 12.45 per 1000 admissions (349 cases) in 2010 (after intervention), with mortality being 73.23% (274 patients) and 66.15% (231 patients) respectively. After adjustment for case mix the intervention was associated with a 19% reduction in the incidence of unexpected cardiac arrest (odds ratio 0.81, 95% confidence interval 0.65-0.98). Conclusions: The RRT was able to detect preventable adverse events and reduce the mortality and incidence of unexpected cardiac arrests.