Introduction: Several studies have found higher in-hospital mortality for admissions during weekend or off hours, known as "weekend or off-hour effect". However, data for this on Malaysian populations is limited. This study was conducted to analyze the 3-year mortality trend in a secondary hospital and its relation to time and date of admission. Methods: The clinical data of 126,627 patients admitted to Taiping Hospital from 1st January 2008 to 31st December 2010 obtained via patient registry database of hospital was analyzed. This study compared mortality during weekdays with weekends, office hours (0800-1700) with off hours (1701-0759), and subanalysis of office hours with evening (1701-2259) or night hours (2300-0759), adjusted for age and gender. Results: Although the overall staff-to-patient ratio is improving, analyses showed a statistically significant increased risk of mortality for those patients admitted during weekends (OR = 1.22; 95% confidence interval [CI] = 1.14-1.31) or off hours in a weekday (OR = 1.67; 95% CI = 1.57-1.78). In the comparison between time of admission, there was statistically significant increased risk of mortality for admissions during evening hours (OR = 1.44; 95% CI = 1.28-1.62) and night hours (OR = 1.92; 95% CI = 1.71-2.16). Diseases of cardiovascular and respiratory system remained the top two causes of death over the three years. Conclusion: The risk of mortality is significantly higher as a result of “weekend or off-hour effect”. Recognition and intervention addressing these issues will have important implications for the healthcare system setting, hospital staffing and training, quality and timeliness of medical care delivery.