The analysis also concluded that there are only seven hospitals that can be considered all-windows best performers. Two of them belong to group A (A6, A15), one (B28) is a member of group B and two (C12, C26) are members of group C and finally two (D5, D13) belong to group D. These seven hospitals are the ones that managed to maintain their full pure technical efficiency in all eight instances of their evaluation against the four different window frontiers. This finding, therefore, suggests that hospital managers and policy makers should pay attention and examine closely and thoroughly their applied practices and technology profile since they can serve as benchmarks for the others. In addition, apart from this small number of the seven all-window best performers, the DEA-window analysis identified also a respectable number of all-window very good performers which we called “semi-efficient”. These are the hospitals that managed to remain fully efficient at least once in every window. It is worth noting that when their results were scrutinized on an individual hospital basis it was found that almost all of them managed to maintain a very high VRS efficiency score in the years that they were not fully efficient. On the other end of the spectrum, the analysis also reported 33 hospitals as being consistently inefficient over all windows. These are 33 hospitals that never managed to achieve a pure technical efficiency score of 100% in any of the years and they are distributed as 6, 14, 7 and 6 in the four groups respectively. Although not all of them can be considered as all-windows worst performers the worst ones are indeed among them. From a managerial point of view, it is clear that this group of hospitals needs also to be scrutinized closely in order to identify peculiarities and possible sources of inefficiency. Hospitals A2, B14, C2 and D9 are the ones with the lowest average efficiency scores (65.8%, 73.3%, 57.7%, 62.9% respectively) over all windows. Among the factors that may explain this finding is the fact that all output/input ratios of these hospitals are among the lowest of their groups throughout all years. Furthermore, hospital A2 is shown to have the lowest occupancy rate (29%) whilst hospitals C2 and D9 exhibit almost a twofold ALoS compared to the average values of their groups. Hospital A2 is located on a rather small island and therefore the low occupancy rate is expected due to the low population. On the other hand, hospitals C2 and D9 are big hospitals located in Athens and are among those covering the more difficult and complicated cases that require longer stays.