The constituencies are spread over Jammu, Kathua and Rajouri districts. Over 18 lakh voters are eligible to decide the political fate of 213 candidates.
Prominent candidates include Sham Lal Sharma (Akhnoor), Raman Bhalla (Gandhinagar), Deputy Chief Minister Tara Chand (Chhamb) and Manohar Lal Sharma (Billawar).
A total of 2,366 polling stations have been set up.
The constituencies going to polls are Bani, Basohli, Billawar, Kathua and Hiranagar in Kathua district, Nagrota, Gandhinagar, Jammu East, Jammu West, Bishnah, R.S. Pura, Suchetgarh, Akhnoor, Chhamb, Marh and Raipur Domana in Jammu district, and Rajouri, Darhal, Kalakote and Nowshera in Rajouri district.
The BJP had won 11 of the 20 seats, the Congress five and the National Conference three. The Peoples Democratic Party had one member.
Polling started at 8 a.m. and will end at 4 p.m. Votes will be counted Dec 23.
In the outgoing 87-member assembly, the National Conference had 28 members, the PDP 21, the Congress 17 and the BJP 11 legislators.