OBJECTIVES: To assess the performance in seven homogenous specialty clinics across all NHS hospitals in the Regional Health Authority of Thessaly (RHAT), over the period 2002-2006. METHODS: Data Envelopment Analysis by using the Malmquist Productivity Index and its decompositions have been applied in order to measure the technical efficiency and productivity.  Clinics were considered to transform inputs labour (medical and nursing staff) and capital (hospital beds) into health services, approximated by the number of in-patient discharges and in-patient days, used as outputs. The model is output oriented and assumes variable return to scale. Data were collected from hospitals’ records. RESULTS: Overall productivity progressed in all clinics, led by technical change rather than technical efficiency. Over the whole period the size of the clinics influences the overall effects on hospital performance and the maximum level of outputs produced has not been achieved using the given labour and capital inputs, except orthopaedic clinics.  The highest productivity changes were achieved by the gynecology (22.5%), the urology (15.7%) and the paediatric clinics (15.4%). All clinics experienced high technological change level, except general medicine clinics which drops by 6.5%. The highest technological changes were experienced by gynecology clinics (48.4%), the paediatrics (26.2%) and ophthalmology (22.1%). CONCLUSIONS: Homogeneity in assessing hospitals’ performance provides evidence on the efficiency and productivity gains among clinics and suggests improvements in those which appear inefficient. The difficult economic situation Greece is facing nowadays makes the assessment of NHS hospitals’ performance a priority in the decision making.