The present study has some limitations which should be taken into account. First, patient severity which may influence utilization and therefore measured efficiency has not been incorporated directly in the study. The lack of relevant data did not allow adjusting outputs for variability in case mix across hospitals. This means that efficiency results may be biased since all outputs are considered equivalent across all facilities. Although it is clear that not all of them are equivalent, it can be considered that this limitation has been adequately remedied as all "special" hospitals were excluded from the study whilst the rest of them were further allocated into four fairly homogenous samples in terms of their size and mixture of services they provide (same clinics/specialties). Consequently, the four groups can be considered as consisting of hospitals with similar case mix. Second, it is worth noting that although the technical aspect of efficiency variations has been covered adequately, the equally important efficiency component that relates to quality variations has been left out in this study due to lack of appropriate and reliable data. It is clear that the establishment of a mechanism for collecting more detailed data in a centralized and systematic way will resolve the afore mentioned limitations and undoubtedly improve the completeness and quality of future efficiency studies.