An analysis of patient records in four different DRG categories estimated direct nursing care requirements. The evaluation of these results showed a great range in direct hours of nursing care, as well as resultant cost of nursing care within and among the DRG categories. Nursing resource use is widely fluctuating based on acuity levels, length of stay, and DRG category. Thus, it was concluded the variables inherent in a model to predict cost rely on determinants of the functional needs of the individual patient.