OBJECTIVES The purpose of this study was to integrate survival function with utility of quality of life to estimate the quality-adjusted life expectancy (QALE) and expected loss of QALE for patients under prolonged mechanical ventilation (PMV). METHODS A total of 633 patients fulfilled the definition of PMV or under such a care for more than 21 days, of which medical records were abstracted and linked to the National Death Registry database of Taiwan to obtain the survival function. Among them we collected 71 subjects and assessed their quality of life by Taiwan version of EQ-5D. The survival function for an age and gender matched reference population was generated using the Monte Carlo method from the life table of the general population of Taiwan. Lifetime survival of the PMV patients were obtained using linear extrapolation of a logit-transformed curve of the survival ratio between the PMV and reference populations. The survival probability for each time point was adjusted with the mean utility to obtain the QALE. RESULTS One year survival rate were 33%. The life expectancy and loss of life expectancy were 32.99 months and 101.89 months in patients with PMV, respectively. The QALE and loss of QALE in patients with slightly clear consciousness were 12.37 quality-adjusted life months (QALM) and 85.39 QALM, respectively. The sensitivity analysis of applying measurements from two proxies, namely, family care-givers and nurses, did not show a statistically significance and the QALE in total patients with PMV were 9.47 and 8.54 QALM, respectively. CONCLUSIONS Overall QALE of patients with PMV was poor and the loss of utility is big. We shall encourage per-protocol weaning procedure in the intensive care unit and early signature for no resuscitation (DNR) when the patient's consciousness was clear.