In the present study we combine Activity Based Costing (ABC) with a microprocess-based custom-made management system used to control of the medical equipment maintenance service performed by a clinical engineering group in a public health institution in Brazil. Results show the cost of service orders calculated through the allocation of the expenditure per cost center to activities performed during the year 2003. As this model can estimate how the activities affect profitability, managers can use ABC information to interpret possible strategies needed to investigate the viability of cost minimization.53508-11