Different scoring systems has been discovered in medical practice, more specifically for ICU treatment, are designed to objectively quantify physiologic derangements and comorbid conditions for estimating mortality, length of stay and ICU resource use. This observational and descriptive study was carried out in the ICU, BSMMU, Dhaka, during March 2014 to May 2016, to determine the association of MSOFA score, CRP level with the outcome of patients on mechanical ventilation as well as compare the MSOFA and CRP combined with MSOFA alone. For this purpose, a total of 60 critically ill patients admitted in the above hospital were included in this study. Patients with an ICU stay of less than 48 hours, readmissions not considered, known case of neuromuscular disease, connective tissue disorder, renal disease and pregnancy and Patients refused to give written consent were excluded from the study. Patients who had MSOFA ≥7, their mean duration of ICU stay were 10.9±6.7 days and mean duration of mechanical ventilation 7.63±5.2 days. Patients who had CRP >11mg/L, their mean duration of ICU stay was 10.8±7.2 days and mean duration of mechanical ventilation was 7.35±5.1 days. Patients who had MSOFA score ≥7 and CRP ≥11mg/L with mean duration of ICU stay was 10.82±7.2 days and mean duration of mechanical ventilation was 7.12±5.2 days. 69.2% patients were CRP status positive (≥11) in death group and 33.3% had alive group. 92.3% patients were Positive (CRP ≥7 or MSOFA ≥11) in death group and 14.3% had alive group. MSOFA identified true positive 32 cases for death, false positive 5 cases, false negative 7 cases and true negative 16 cases confirmed by patient's outcome. CRP level identified true positive 27 cases for death, false positive 7 cases, false negative 12 cases and true negative 14 cases confirmed by patients outcome. Combined (CRP ≥11mg/L and MSOFA score ≥7) identified true positive 33 cases for death, false positive 1 case, false negative 6 cases and true negative 20 cases confirmed by patient's outcome. We concluded that there is a positive correlation (r=0.323; p=0.014) between CRP status with MSOFA score, positive correlation (r=0.402; p=0.002) between MSOFA score with MSOFA score and CRP combined and a positive correlation (r=0.999; p=0.001) between CRP level with MSOFA score and CRP combined.