NY 81 begins at an intersection with
NY 145 and Potter Hollow Road (unsigned
NY 910G) in the hamlet of Cooksburg (in the town of
Rennselaerville). NY 81 proceeds eastward through Rennselaerville, as a two-lane rural roadway, paralleling and crossing some power lines. After turning to the southeast, NY 81 crosses into the
Greene County town of
Durham. Entering the hamlet of Oak Hill, the route becomes a two-lane residential street, intersecting with the terminus of
County Route 22 (CR 22; Oak Hill Road). After CR 22, NY 81 bends eastward out of Oak Hill, intersecting with the northern terminus of
CR 27. Paralleling a nearby creek,
CR 67 forks to the southeast, while NY 81 continues on its right-of-way through Durham. NY 81 bends northeastward, intersecting with the northern terminus of
CR 75, where it turns eastward into the town of
Greenville. In Greenville, NY 81 is the main street, remaining a two-lane residential street. Intersecting with
CR 50 (North Road). NY 81 continues eastward through Greenville, returning to being a rural two-lane highway and entering the hamlet of West Greenville. A short distance eastward, NY 81 enters the hamlet of Greenville, where it doubles as a residential-commercial street, where it crosses
NY 32. After NY 32, the route forks to the southeast at an intersection with
CR 26, which is quickly connected via
CR 26A. Gradually bending eastward through the town of Greenville, NY 81 intersects with the northern terminus of
CR 41 (Greenville Center Road). After CR 41, NY 81 bends to the southeast once again, winding past at an intersection with
CR 35 (West Road), which terminates there. Making a dart eastward, NY 81 turns to the southeast past the hamlet of Surprise, where the route becomes a rural two-lane roadway once again. Just after Surprise, NY 81 enters the town of
Coxsackie, winding southeastward past an intersection with
CR 45, entering the hamlet of Earlton. The route remains rural, crossing intersections with
CR 51 and
CR 9 (Old Plank Road), bending to the northeast. Intersecting with a former alignment of itself, NY 81 turns eastward, intersecting with the eastern terminus of CR 26. After CR 26, NY 81 crosses over the
New York State Thruway (
I-87) then parallels another former alignment of itself. Through Coxsackie, NY 81 intersects with
US 9W in a small commercial strip. This serves as the eastern terminus of NY 81, which continues eastward as
NY 385 (Mansion Street). ==History==