The report was prepared by the consulting firm McKinsey & Co. and the United States-Japan Trade Study Group, which represents business and government from both countries.
While US executives see much to praise in the report, they still point out specific problems they say need to be addressed.
The US share of direct foreign investment in Japan has declined, the study acknowledges. It also recognizes the US trade deficit with Japan, which US officials claim totaled $20 billion last year. And meeting Japanese product standards is not easy, it admits.
But there are a lot of ''on the other hands'' that need considering, the report says.
On the other hand, US companies produce and sell annually about $20 billion worth of goods and services in Japan. Japanese operations in the US total about are goods produced locally.
And, on the other hand, trade figures don't include oil shipped by US companies to Japan which came from outside the US - a total of $21 billion in 1980.
* Financial services: Consumers are changing in Japan. They are getting older and want higher interest on their savings. They could use US expertise in pension funds and money market management, the study says. Corporations are interested in more international investing, an area where the US has a good track record. US international banks and insurance companies could work with regional Japanese banks gaining consumer access in addition to corporate access.
However, says Martin Weiss, editor of Money Forecasts in West Palm Beach, Fla., ''serious obstacles'' get in the way of business. Mr. Weiss advises a major Japanese brokerage firm.
The biggest obstacle is ''the wall'' between brokerage firms and banks. ''That refers to a very solid, protective shell which surrounds the entire banking industry and prevents any other industry from making inroads on their saver market,'' he says.
Weiss says money funds had a tough time starting in Japan, and US firms trying to edge in on the securities business find it ''rough - the market isn't big enough to begin with.'' He thinks two businesses could do very well in Japan: foreign-security firms in the institutional market and financial-planning firms.
* Medical management: The report does not paint a bright picture of Japanese hospital management. Financial failures of hospitals and shortages of qualified personnel and nursing homes are some of the problems.
But there's a major disincentive to outside participation: Japanese hospitals must be owned by a certified medical doctor, and cannot be run for profit, nor offer dividends.
* Computer services: The Japanese are weak on software development, but US companies ''will have to move quickly'' to take advantage of this, the study says. One area, known as CAD-CAM, computer-aided design and manufacturing, is especially attractive. Over 80 percent of CAD-CAM systems used in Japan are from the US, the study says.
An official at Computervision Corporation in Burlington, Mass., says Japan is a ''high growth'' market, but that US CAD-CAM companies need to watch out. They must pay attention to specific applications needed by the Japanese, and supply support and servicing of their product. Computervision Corporation has about a third of the Japanese market.
Other kinds of software need bolstering in Japan: operating systems software - the internal nuts and bolts software that makes computers run - and applications software, programs that accomplish specific tasks, such as budget balancing or word processing.