Inventors who take on the expense of filing patents in a foreign country expect financial returns that justify the additional costs, according to a National Science Foundation report. The brief compares patents issued in 12 countries, reporting that "in most parts of the world, foreign inventors account for a much larger share of patent activity" than in the US. In Canada, Mexico and Italy, more than 90 percent of patents issued went to foreigners. Patents by foreigners In the US, foreign inventors accounted for roughly 45 percent of the more than 147,000 patents awarded in 1998, according to the Patent and Trademark Office. Of the nations studied, only Japan and Russia granted fewer patents to nonresident inventors -- less than 20 percent in each country. Alan Engel, president of International Science and Technology Associates in Haverford, Pa., said filing a foreign patent is not a cultural labyrinth. It requires a strategy that takes into account the local laws and patent system. Photonics companies netted a large number of US patents in 1998. Sony Corp. in Tokyo, Eastman Kodak Co. in Rochester, N.Y., and Lucent Technologies Inc. in Murray Hill, N.J., received 1316, 1124 and 928 patents, respectively.