After several decades of robust growth in health spending, the efficiency of these expenditures is coming under closer scrutiny. Using the detailed description of short-stay procedures supplied by the “Programme for Medicalization of Information Systems” (Programme de Médicalisation du Système d'Information: PMSI), we can analyze trends in the economic performance of healthcare establishments. We aim to define a total productivity index based on the estimation of a public-hospital production function for the period 2003-2007. The activity indicator chosen is the sum of stays or procedures by homogeneous patient group, weighted by the costs observed in a sample of hospitals in 2003-2004. In essence, therefore, this indicator assumes constant healthcare quality. We seek to measure activity as a function of personnel composition as well as the establishments' other observable characteristics including size and a technical equipment index. The productivity index measures the share of activity unaccounted for by the levels of these various explanatory factors. Our analysis yields several structural findings, such as the greater productivity of hospitals performing a higher proportion of surgical or obstetrical procedures, and the existence of an efficiency ceiling at a size of around 800 beds. There are two significant time trends: a rise in public-hospital productivity for short stays between 2003 and 2007, and a narrowing of productivity gaps between legal entities.