This manual has been prepared by the OECD Secretariat in conjunction with theWorking Party of National Experts on Science and Technology Indicators (NESTI) inorder to provide users and producers of patent statistics with basic guidelines forcompiling and analysing these data.The importance which the OECD attaches to the use of patent statistics goes backto the late 1970s. The OECD issued a first edition of this manual in 1994. At the “Blue Sky” conference on “New science and technology indicators for a knowledge-based economy”, organised by the OECD in 1996, experts identified patents as a promising avenue for improving our quantitative understanding of science and technology (S&T) activities in a rapidly evolving economic and policy context. Since then, statistical work on patents has advanced significantly, at the OECD, in member countries and in academia. This manual takes account of these developments.The manual shows what patent statistics can be used for, what they cannot beused for, and how to count patents in order to maximise information on S&T activities while minimising “noise” and bias. Patent data provide unique insights into the processes and outcomes of inventive activities (e.g. the location of inventive activities, inventive networks, emerging technologies, etc.). Used with other data, they support the analysis of other dimensions of innovation that are of policy interest, such as the role of intellectual property in economic performance, entrepreneurship, and the tracking of linkages in the S&T system. Yet, patent-based indicators suffer from several weaknesses and, as a result, they should be designed and interpreted with care, hence the need for this manual.