Universities and companies are rushing to the patent office in record numbers to patent nanotechnology inventions. This rush to the patent office is so significant that many law firms have established nanotechnology practice groups, and the U.S. Patent and Trademark Office has now created a new technology class designed to track nanotechnology products. Three big differences between the emerging science of nanotechnology and other inventions make the role of patents more significant here than elsewhere. First, this is the first new field in a century in which people started patenting the basic ideas at the outset. In most other fields of invention over the past century - computer hardware, software, biotechnology, the Internet - the basic building blocks of the field were unpatented. In nanotech, by contrast, companies and universities alike are patenting early and often. A second factor driving the importance of patents in nanotechnology is its unique cross-industry structure. Unlike other new industries, in which the patentees are largely actual or at least potential participants in the market, a significant number of nanotechnology patentees will own rights not just in the industry in which they participate, but in other industries as well. This may significantly affect their incentives to license the patents. Finally, a large number of the basic patents have issued to universities, who have become far more active in patenting in the last 25 years. While universities have no direct incentive to restrict competition, their interests may or may not align with the optimal implementation of building-block nanotechnology inventions.