Background: Critical illness refers to a wide spectrum of life-threatening medical or surgical conditions usually requiring an intensive care unit level of care. In most of these patients a common pathophysiological process is often present, namely infection, trauma, or major surgery. These factors initiate an inflammatory cascade leading to activation of regulatory mechanisms in order to control the intensity of the inflammatory response. The prognosis of critically ill patients usually depends on illness severity, intensity of the biological inflammatory response and nutritional status. Objective and Methodology: This analytical cross-sectional study of 82 mechanically ventilated critically-ill patients with hypoalbiminemia admitted in the ICU and NCCU of St. Luke’s Medical Center from January 1 to December 31, 2008, aimed at determining the odds ratio between hypoalbuminemia and those with albumin >3mg/dl in terms of failure in weaning. Also it seeks to determine the prevalence of hypoalbuminemia among mechanically ventilated patients in the ICU; characterize the patients involved in the study in terms of age, sex, APACHE II score, and co-morbidities/ underlying illness; and to determine the manner of serum albumin correction. A 2x2 table analysis was computed to measure the odds ratio. Chi-Square for qualitative dichotomous variables and unpaired t-test for continuous variables are the statistical tools employed to interpret the present data. Results: Eighty-two of the 109 of patients had hypoalbuminemia, giving a prevalence of 0.75. Of the 82 hypoalbuminemic patients, 26 subjects failed to be weaned off mechanical ventilator support compared to two subjects of 27 patients with no hypoalbuminemia. An odds ratio of 5.8 was obtained. Patient’s demographics of both groups did not significantly differ except for hypertension. The biochemical parameters prior to weaning (hemoglobin, sodium, potassium, calcium and magnesium) were not significantly different between hypoalbuminemic and non hypoalbuminemic patients. From our results, 22.6% of the patients were started on albumin IV infusion at a level of <2.4g/dL. The rest did their correction through diet. Conclusion: Hypoalbuminemia with a serum albumin level of <3mg/dl is associated with negative outcome of weaning from mechanical ventilation. The odds that a patient will have failure in weaning was 6 times more likely in subjects with serum albumin <3 mg/dl.