A representative of the Kyrgyzstan Central Election Commission (CEC) told RFE/RL that preliminary results are expected to be announced on the morning of April 30.
A candidate needs more that 50 percent to get elected. If the percentage is not reached, candidates with the most votes face a second round of voting.
The CEC says voting was held without any incidents taking place.
The elections are being observed by the OSCE, NGO representatives, human rights campaigners, representatives of Kyrgyzstan Ombudsman's Office, and political parties. Turnout by noon Prague time was at about 40 percent.
Meanwhile, Bermet Akaeva, the daughter of ex-President Askar Akaev, was hospitalized on April 29 after she was summoned by the Kemin district Prosecutor's Office. She was barred from the by-elections by a district court and the ruling was upheld by the Kyrgyz Supreme Court.
She told RFE/RL that she cannot change anything in the election, but that she will continue to struggle to prove that she has a legal right to participate in the elections as a candidate