The Pachaug Trail is a 28-mile (45 km) Connecticut hiking trail and is one of the Blue-Blazed hiking trails maintained by the Connecticut Forest and Park Association. It is a horseshoe shaped trail.

The trail is located in the towns of Voluntown in New London County and Sterling in Windham County in eastern Connecticut as well as Hopkinton, Rhode Island. The trail is mostly within the Pachaug State Forest.

The Pachaug Trail was a much larger trail in the 1930s and 1940s but it has been one of the Blue-Blazed Trails most drastically shrunk by post-World War 2 housing developments.

The Pachaug Trail is a Blue-Blazed hiking trail and extends from Breakneck Road near the intersection with Lee Road in Griswold, Connecticut, to northern Spaulding Road in Plainfield. Most of the Pachaug Trail is on state land within the Pachaug State Forest. It connects to public recreation areas maintained by the Connecticut Department of Environmental Protection at Green Falls Pond and Phillips Pond in Pachaug State Forest.

Much of the Pachaug Trail is flat or has gradual ascents and descents and is suitable for casual walking or hiking, running – or snowshoeing in the winter. The steepest section is where the trail traverses the closed section of Flat Rock Road. The Quinebaug Trail crosses streams and wetland areas that are subject to flooding in periods of significant rain and snow melt. In particular, the trail sections close to Hell Hollow Pond and Lockes Meadow Pond are low-lying areas which are often under water.

The trail connects to other Blue-Blazed trails in Connecticut's Pachaug State Forest: the Quinebaug Trail in the Philips Pond through Flat Rock section, and the Nehantic Trail at Green Falls Pond. The Nehantic and Pachaug trails overlap for a section which includes Mount Misery and the Chapman Management Area (which includes the Rhododendron Sanctuary Trail). Lee and Breakneck Roads connecting these two trails and is marked with blue and red blazes (a blue blaze with a red bar in the lower half of the blaze). There are three connector trails from the Quinebaug to the Pachaug trail: The Quinebaug-Pachaug Crossover trail from the Quinebaug at Philips Pond to the Pachaug marked with blue and red blazes, the section of Hell Hollow Road between the two trails marked with marked with blue and red blazes, and the Pachaug-Quinebaug Crossover trail marked with yellow blazes.

The southern end of the Pachaug Trail starts on Breakneck Road in Griswold Connecticut, just north of the intersection with Lee Road and at the northern end of the Nehantic-Quinebaug Crossover trail. The trail leads generally north, connecting with the Quinebaug-Pachaug Crossover trail and Trail 1 forest road at Phillips Pond and then closely paralleling the Trail 1 forest road until crossing Hell Hollow Road to the west of Hell Hollow Pond. The trail continues through woods and then joins with the non-vehicular and closed section of Flat Road until they pass over the top of Flat Rock (41°39′31″N 71°52′19″W / 41.65861°N 71.872°W / 41.65861; -71.872). The trail diverge west of the Flat Rock "summit", with the Quinebaug Trail turning to the north to closely follow the western banks of Lockes Meadow Pond before veering north-west to its northern terminus on Spaulding road north of Dow Road in Plainfield Connecticut.

There are multiple connecting main and side trails with parking available at each recreational area.