Considers the value of patents as sources of business information in view of their variable and inconsistent quality, bearing in mind that only 2% of patented inventions become commercial products. Discusses a range of factors involved in using patent information, including: national and regional patents; access to patent information; and the role of specialist patent libraries (with particular reference to the British Library, Science Reference and Information Service (BL SRIS)); and the use of patents as indicators and sources of commercial intelligence, involving patent analysis by country and company and use of citation analysis techniques.