Diagnostic services are regarded as important hospital services, which are very costly due to the use of advanced technologies and facilities, and it seems so necessary to calculate and analyze the costs thereof. Understanding the profitability of lab services by traditional and ABC method that provided by military units is the purpose of the study. This study was an applied retrospective study that conducted in a lab of Iran in a hospital of military unit in 2015. After identifying the overhead and final centers, costs related topics were collected, and cost price of the final services was calculated using Activity-Based Costing method. Calculated cost of services had been consequently compared average tariff of common services using the principles of sharing. According to the results, there were deviations between average service tariff and per admission, and most services provided to armed forces were losing. The lab was no profitable in both methods but losses in ABC were more estimated. For Pathology, Blood Bank, Biochemistry, and Hematology tests, we were witnessing the greatest deviation from the tariff but Immunology, Serology and Microbiology tests were profitable.