Purpose The purpose of this paper is to present a practical instrument for self-evaluation of maturity in the processes of procurement and supply management, applicable to small and medium-size companies, as well as to show how the use of this evaluation tool may help companies to decide what to improve in these processes. Design/methodology/approach Based on an empirical and theoretical framework, the instrument developed measures the maturity of procurement and supply management activities in four macro-processes: materials management, purchase process, supplier evaluation process and process of procurement planning. For testing the self-evaluation instrument, the authors evaluated the maturity of 48 hospitals and 37 metal-mechanic manufacturing companies located in the southern region of Brazil. To show how to use this tool to decide what to improve in procurement and supply processes, the authors conducted a comparative analysis of a hospital and a metal-mechanic company, in relation to the sample of the same segment. Findings The results show that the instrument is reliable for practical application. Metal-mechanic industries have a greater maturity in the purchase process than in the other three macro-processes. The management of materials is the most mature macro-process in hospitals. Comparing hospitals to metal-mechanic companies, the present research shows that, between 20 and 99 employees, hospitals tend to have a higher level of maturity in the purchase process than metal-mechanic companies. With 100 employees or more, metal-mechanic companies are more mature than hospitals in procurement planning and in selection/evaluation of suppliers. Originality/value Presenting a useful self-evaluation instrument, this work demonstrates that the measurement of the maturity level, and benchmarking it with other companies, may help a firm to decide what to improve in its processes of procurement and materials management, showing how an economic sector can understand itself better. Few scientific studies have practical application to the assessment of the degree of maturity of procurement and supply management processes. Besides that the authors did not find other papers presenting a comparison of different segments.