Lefty began fly-fishing in 1947 while serving as a guide for the famous fly fisherman Joe Brooks. In 1964 he moved to Miami, Florida and began to fish for salt water species in the Florida Keys. It was during this time that Lefty Kreh, Joe Brooks, Al Pflueger, Tom McNally, George Hommel, Stu Apte and others pioneered the techniques that modern salt water anglers use to pursue fish with fly fishing gear.

In addition to his fishing accomplishments, Lefty has been an active outdoor writer for more than forty-five years. He has written for most major outdoor magazines. He is the retired outdoor editor of The Baltimore Sunpapers and holds a staff position on several outdoor magazines. He is also an accomplished photographer.

The Lefty's Deceiver is an artificial fly commonly categorized as a streamer fly which is fished under the water surface. It is a popular and widely used pattern for both predacious freshwater and saltwater game fish and is generally considered one of the top patterns to have in any fly box. Lefty Kreh invented the Deceiver fly in the late 1950s as a streamer that would be easy to cast in wind and would not "foul" (or wrap around the bend of the hook) a common problem for older streamer patterns. The original Lefty's Deceiver was tied in an all white pattern, but fly tiers have recreated the pattern in a variety of colors. A darker colored top with a lighter bottom (mimicking the various forage fishes that larger fishes feed upon) is the most popular design. The Deceiver is arguably the best known saltwater fly pattern in the world and in 1991 the U.S. Postal Service honored Kreh’s creation with a postage stamp.

In 2010, the first Lefty Kreh Flyfishing Challenge Course was built as the centerpiece of instruction at HomeWaters University, which is located in Spruce Creek, Pennsylvania. Lefty designed the course himself, incorporating dry land, still water and moving water into various casting stations. Lefty calls it a “challenge” course, as opposed to a “casting” course, because he included real-world fly-fishing conditions. Scenarios include the need for long casts, short and precise presentations, casting into the wind, casting with no room for a back cast, and dealing with boulders, rapidly moving water, logs and other floating debris.

HomeWaters University opened in June 2010 and offers fly-fishing classes. Its 20 fishing guides take on students of any skill level, beginning to expert, and teach them casting techniques, as well as how to catch a fish. The two-day long courses are held at the confluence of Spruce Creek and the Little Juniata River.

In 2003 Lefty Kreh was inducted to the International Game Fish Association Hall of Fame.

Lefty received the prestigious "Lifetime Achievement Award" by the American Sportfishing Association, has been honored with the "Lifetime Contribution Award" by the North American Fly Tackle Trade Association and is also in the Freshwater Fishing Hall of Fame. In 1997 he was named "Angler of the Year" by Fly Rod and Reel Magazine. Lefty has served a number of years as Senior Advisor to Trout Unlimited, the Federation of Fly Fishers.

In addition to "Fly Fishing in Salt Water", other submissions by Lefty include:

• "Tying Flies That Catch Fish"
• "Everything Anglers Need to Know by the World's Foremost Fly-Fishing Expert"
• "Saltwater Fly Patterns"
• "The Compact, Practical Handbook That Will Add Ten Feet--Or More--To Your Cast"
• "And Other True Fishing Tales"
• "A Practical Guide to the Most Important Element of Fly Fishing"
• "Lefty Kreh on Fly Casting"