The Beech River is a stream draining the east-central portion of West Tennessee. The Beech rises about five miles (eight km) northwest of Lexington, Tennessee, the county seat of Henderson County. In the same area are the headwaters of two other West Tennessee Rivers, the Big Sandy River and the Middle Fork of the Forked Deer River. The Big Sandy, like the Beech, is part of the Tennessee River system, whereas the Forked Deer system drains into the Mississippi River.

The Beech River system is somewhat unusual for this region in that all of its major tributaries (a total of eight) are impounded, one of them twice, primarily by dams built in the mid 20th century as part of the Tennessee Valley Authority's Beech River Project. None of these dams are for the purposes of power generation, unlike most other TVA dams; the size of the streams impounded and their relative lack of fall would make power generation impractiable. These dams are for purposes of flood control and recreation; it is possible that the relatively small volume of water they store could result in some mininal aid to navigation on the Tennessee under some conditions. The main stream of the Beech is impounded as well at one point into Beech Lake. Some of these lakes are in Natchez Trace State Park and Forest , the largest of the Tennessee state parks, located many miles west of both the Natchez Trace Parkway and the historic Natchez Trace; this area is named for a branch of the historic Trace that bore that name in the area.

The Beech flows southeast into the town of Lexington and then primarily eastward afterwards. As is typical of most major streams in West Tennessee, much of the lower course was the subject of a channelization prohect in the mid-20th century conducted largely for agricultural purposes; this has resulted in a considerable loss of wetlands. The stream crosses into Decatur County, flowing in between the only two sizeable towns of that county, Parsons, the largest town, and Decaturville, Tennessee, the county seat. The large embayment formed at the mouth of the Beech is the result of the backwaters of the Kentucky Dam project many miles downstream on the Tennessee; the embayment reaches the outskirts of both towns. Very near the mouth of the Beech is the town of Perryville , the county seat of the entire area when Perry County consisted of all of what is now both Perry County and Decatur County in the early 19th century.