Mechanical ventilation (MV) predisposes patients to numerous complications, which increases with longer durations of treatment. Identifying individuals more likely to require prolonged MV (PMV) may alter ventilation strategies or potentially minimize the duration of therapy and its associated complications. Our aim was to identify clinical variables at the time of intubation that could identify individuals who will require PMV.One hundred thirty consecutive adult patients requiring MV support in a medical intensive care unit (ICU)were retrospectively assessed. Prolonged MV was defined as MV support more than 14 days.Mean age was 62.3±21.1 years, 64.6% were men, and mean duration of MV support was 11.4±11.9 days. Prolonged MV was required in 31.3%. Requiring intubation after admission to the ICU, heart rate greater than 110, blood urea nitrogen more than 25 mg/dL, serum pH less than 7.25, serum creatinine more than 2.0 mg/dL, and a HCO3 less than 20 mEq/L were the only variables independently associated with PMV. Specificity for predicting PMV was 100% with 4 or more of these variables.The novel predictive model, using Intubation in the ICU, Tachycardia, Renal dysfunction, Acidemia, elevated Creatinine, and a decreased HCO3, was highly specific in identifying patients who subsequently required PMV support and performed better than Acute Physiology Age Chronic Health Evaluation III.