In this paper we analyse the existing interrelationships between information technology (IT) and the adoption of lean production. More specifically, the level of adoption of lean production is studied in accordance with the degree of use and the kind of IT used (internal and external IT). The results of the study show how companies need to augment the degree of use of internal or intra-organisational IT in order to increase the level of implementation of lean production and therefore improve efficiency. Results also show that external or inter-organisational IT only has a significant negative influence on the level of adoption of lean production when internal IT is controlled. These findings provide managers with empirical evidence and a theoretical framework on the balance between internal and external IT in order to increase lean production adoption, thus offering practical guidance on how to manage IT and lean production adoption.