Introduction: Knowing factors associated with clinical deterioration among hospitalized patients will aid clinicians in predicting and early identifying patients and will therefore prevent adverse events and improve patient outcomes. Objectives: To identify predictors of clinical deterioration among adult patients hospitalized in general wards. Methods: Matched case-control design was used in this study. Data of 2500 patients were retrospectively collected from two tertiary hospitals in Oman that utilize Critical Care Outreach Team (CCOT) to respond and rescue deteriorated patients hospitalized in general wards. All adult patients hospitalized in medical or surgical wards of the two tertiary hospitals who deteriorated clinically and needed CCOT activation between February 2016 and February 2017 were included in the case group (ncase=500). Each patient in the case group was randomly matched with four adult patients who were admitted in the same hospital and wards during the same time period but did not deteriorate or need CCOT activation (ncontra-2000) making the total sample size N=2500. Descriptive, bivariate correlation, and multivariate regression analyses were conducted to describe the study variables and evaluate their association with and prediction value of clinical deterioration. Results: For the total sample, ages ranged from 18 to 107 years with a mean of 49.1 years (SD = 20.36 years. More than half of the study sample were female (54.8% while male patients made up 45.2% of the sample. Multiple regression analysis produced strong and moderate predictors for clinical deterioration including: Male gender (OR = 1.48, 95% CI: 1.137 – 1.927, p = 0.004), diagnosed with sepsis (OR = 6.17, 95% CI: 2.66 – 14.30, p < 0.001), diagnosed with cancer complications (OR= 2.77, 95% CI: 1.123 – 6.686, p = 0.027), having multimorbidity (OR = 7.64, 95% CI: 4.45 – 13.06, p < 0.001), delayed (referral from secondary or primary facilities) (OR = 5.99, 95% CI: 3.411 -10.54, p < 0.001), and severity of clinical presentation as measured by MEWS (OR = 2.99, 95% CI: 2.66 -3.34, p<0.001). Conclusion: Male gender, admitting diagnosis of sepsis and cancer-related complication,multimorbidity, referral admission, and high modified early warning score (MEWS) on admission can serve as predictors of clinical deterioration of adult patients during hospitalization.