The Nadaswaram also called Nagaswaram is one of the most popular classical instruments of south India and the world loudest non-brass acoustic instrument similar to the north Indian Shennai, but larger, with a Harwood body and a large flaring bell made of wood or metal.

In India the Nadaswaram is considered to be very auspicious, and it is the key instrument which is played in all Hindu marriages and temples in south India. The instrument is usually played in pairs, and accompanied by a pair of drums called Tavil.

Belongs to the woodwind family known as a “Mangala Vadya” (‘Mangala’ means auspicious, vadya means instrument) since it is played in temples, processions, festivals and auspicious occasions like marriages, etc. It is a double reed instrument with a conical bore which gradually enlarges toward the lower end. It is usually made of a type of ebony called Aacha, a very light wood. The longest Nadaswaram is said to be 95 cm or 37 inches. A double reed is attached to the top portion, known as Seevali or Naruku. Beside spare reeds, a small ivory or horn needle (known as kuchi) is attached to the Nadaswaram. The needle is used to clear the mouth piece of saliva particles and allows the free passage of air. A separate bell shaped portion is attached to the bottom of the main bore (called anasu). It is made out of the same wood.

The Nadaswaram has seven finger-holes. There are five additional hole drilled at the bottom which are used as controllers. The Nadaswaram has a range of two and a half octaves like the flute. The system of fingering is similar to that of a flute. , but unlike the flute, where semi and quarter notes are produced by the partial opening and closing of the finger hole, in the Nadaswaram it is produced by adjusting the pressure and strength of the air-flow into the pipe. Hence it is a very exacting instrument. Also due to its intense volume and strength it is basically an outdoor instrument and much more suited for open spaces then for closed indoor concert situations.

Some of the greatest early exponents of the Nadaswaram include, Sembanarkovil Ramaswamy Pillai, Chidambaram Vaidyanatha Pillai, Thiruvangadu Subramania Pillai and Isai Perarignar Nadaraja Sundaram Pillai. In the more recent times Karukurichi Arunachalam, Sheik Chinna Moulana, are well known Nadaswaram artists.

U.S. composers such as Lewis Spartlan and Carl Stone have expressed admiration for the Nadaswaram, and a few jazz musicians have taken up the instrument: Charlie Mariano is one of the non-Indians able to play the instrument, having studied it while living in India; and Vinny Golia, J. D. Parran and William Parker have recorded with the instrument. Tim Price, a student of Charlie Mariano at Berkley, also plays the Nadaswaram. The German saxophonist Roland Schaeffer also plays it, having studied from 1981 to 1985 with Karupaia Pillai.