We have studied a large, random sample of U.S. patents issued between 1996 and 1998. We collected a variety of information about these patents, including area of technology, national origin, the number of inventors, nature and size of the owning entity, the number and type of prior art references, and the time spent in prosecution. We seek to establish relationships between a number of variables in issued patents-such as number of inventors, numbers and types of references to the "prior art," numbers and types of "claims," and length of time between application and issuance-and a number of defined areas of technology. We identify the countries in which particular inventions originated--almost one-half of all issued U.S. patents cover inventions originating in other countries--and test for relationships between the above variables and countries of origin. We also evaluate relationships between countries of origin and areas of technology. The conclusions are somewhat surprising, and point to a patent system that is far from unitary in the way it treats different inventors and different inventions.