(FORTUNE Magazine) – What do Amorim, Loctite, and Krones have in common? Besides the fact that they all sound like rare diseases, they're three obscure multinational companies that command a 70% to 80% worldwide share of their markets.

A quick glance at these markets and you understand why you've never heard of them. Amorim, a Portuguese company, is the world leader in wine corks. The German Krones AG has a proud 55-year tradition of making machines that put labels on beverage bottles. And the U.S. company Loctite dominates the world market in anaerobic adhesives--the glue that you would use to seal metal parts of, say, self-assembly lawn furniture.

These and 497 other similarly recondite yet extraordinarily successful companies were unearthed by German consultant Hermann Simon during a sedulous, six-year research project. Simon visited 120 small and midsize companies (between $50 million and $1 billion in revenue) to find out what makes these so-called Hidden Champions tick. What he found convinced him that these unknown companies have some things to teach the Fortune 500. Examples:

--Hidden Champions focus on doing one thing well. Take the Spanish manufacturing company Chupa Chups, for instance. In 1957 it decided to discontinue some 200 products and focus on one--lollipops. It now dominates the world market. Such singular concentration has also paid off for the Minneapolis-based St. Jude, which became seven times larger than its nearest competitor by concentrating almost exclusively on heart valves.

--Hidden Champions avoid focus groups and instead engage in one-on-one interaction with customers. Heinz Hankammer, founder and CEO of Brita HG, began his assault on the U.S. market for in-house water filters 10 years ago by sitting in drugstores and demonstrating to Utah housewives the marvels of his company's products.

--Hidden Champions believe that the best talent around is happily toiling within their own ranks. The average tenure of CEOs at these companies is a remarkable 21 years; Haribo, the world leader in candy gummi bears, has had just two CEOs in 76 years.

--Hidden Champions have little regard for management buzzwords like "outsourcing" and "strategic alliances." They believe that nobody knows their business better than they do. Chupa Chups designs 80% of its own machinery, and it turns down any and all offers for supply contracts and joint ventures.

For Hidden Champions, the result of all these tactics has been big sales gains--and very little fame. That's a tradeoff easy to live with.