California and Maryland hospital data are used to estimate the incremental cost associated with 64 categories of hospital acquired complications. The reason for admission, severity of illness at admission and the presence of hospital acquired complications are used in a linear regression model to predict incremental per patient cost yielding an adjusted R2 of 0.58 for Maryland data and 0.60 for California data. The estimated incremental cost due to each of the 64 categories of complications was consistent across both databases and accounted for an increase in total short term acute inpatient hospital cost of 9.39 percent in the California data and 9.63 percent in the Maryland data.