Introduction The public sector has during the last decades been struggling with the challenge of how to increase the efficiency, the quality of performance, as well as with problems related to work environment and recruitments. Hospitals have struggled with increased focuses on costumer orientation, rationalizations and care processes redesign, and have often used Lean production (LP) as management model.

Aim to assess the long-term importance of implementing LP in hospitals for the psychosocial work conditions.  Based on earlier research (e.g. Westgaard & Winkel, 2011), the following hypothesis were tested (1) Strategic large scale  implementation of LP is associated with negative impact on mental health; (2) Implementation of LP is associated with weak negative impact on psychosocial work conditions; (3) The association between implementation of LP and psychosocial conditions is moderated by profession and participatory approaches.

Method  Five hospitals working with improvements of care processes were studied 2012-2014 using questionnaires to employees (T1 n=1303) and interviews at strategic and operative levels. Analyzes with mixed models repeated measurements were performed. The explaining variables for the models were implementation of lean at strategic resp operative level, and time (T1, T2, T3). The outcome variables were work-related health (SRH, work ability, stress-symptoms) and psychosocial work conditions.

Results  Physical, cognitive and mental stress-related symptoms were only weakly associated with strategic or operative LP initiatives. There were no overall differences in self rated health and work ability with regard to implementation of LP. A higher degree of LP at operative level was associated with decreased work demands. There was, especially initially, more beneficial or improved working conditions in relation to higher degree of LP at operative levels. The long-term follow-up showed that quantitative demands increased and predictability as well as leadership decreased in the non-lean hospitals. There were different patterns with regard to profession and participatory approaches that will be presented.