Relevant costing is a management accounting term that relates to focus on only the cost relevant to a specific decision being made. Irrelevant costs are excluded from any incremental decision-making problem because they are supposed to have equal effects on all the available alternatives ( Dillon, R. D. and, J. F. Nash, 1978). This study adopts an observation of quantitative method with primary and secondary data in view of the nature of the analysis. Relevant costing is often used in short-term decision-making and a number of specific practical examples are illustrated in this study. This study has designed to make the aim of assessing the level of perceptions of four areas such as (i) making and buying; (ii) dropping or retaining a segment; (iii) constrained resources; and (iv) special orders; in using relevant costing in Ready-Made Garments (RMGs) industry of Bangladesh. To meet this aim total 100 companies as a sample from Ready-Made Garments (RMGs) industry have been randomly selected. By using variance analysis, authors have found that all four factors have significant influence in using relevant costing. Last, the result of this study suggested that the strengthening the decision-making mechanism required a strong relevant costing benefits and its proper application.