New York State Route 338 (NY 338) was a 7.04-mile-long (11.33 km) state highway in Washington County, New York, in the United States. The western terminus of the route was at NY 40 in South Argyle, a hamlet in the town of Argyle. Its eastern terminus was at NY 29 in Greenwich. NY 338 connected both highways to the hamlet of Cossayuna and nearby Cossayuna Lake in northeast Greenwich.