National Highway 183A, also known as NH 183A, is a National Highway in the Indian state of Kerala that runs from Chavara Titanium Junction, Kollam, to Vandiperiyar via Adoor and Pathanamthitta. It is the 4th National Highway passing through the Kollam district.

Adoor is a municipality in the Pathanamthitta district of Kerala, India. It is the headquarters of the Adoor Taluk and Adoor Revenue Division. Adoor is located 18 km (11.2 mi) southwest of the district headquarters Pathanamthitta and 85 km (52.8 mi) north of the state capital Thiruvananthapuram.