This paper presents a quality index for patent systems. The index is composed of nine operational design components that shape the transparency of patent systems and affect the extent to which they comply with patentability conditions. Seven factors are related to rules and regulations (e.g., grace period, opposition process and continuation-in-parts), while two factors measure patent offices’ resource allocation policy (i.e., workload per examiner and incentives). The index is computed for 32 national patent systems, it displays a high heterogeneity across countries. Cross-sectional quantitative analyses suggest that the demand for patent rights -or the propensity to patent- is lower in patent systems with a higher quality index, controlling for research efforts, patent fees and the “strength” of enforcement mechanisms.