Costing a service product is a challenging but important tool for cost control. Different methods used for costing may provide varying costs and the choice of the method used becomes important. Use of absorption costing and marginal costing method and treatment of labour cost as variable and fixed cost provided different results in the present study of the cost of below knee patellar tendon bearing prosthesis. The study shows that marginal costing should also be done along with the absorption cost as it provides better indicator for cost control.