While Bihar, where bypoll was held in ten seats, recorded the lowest turnout of 46.42 per cent, the three constituencies in Karnataka saw 72 per cent polling followed by Madhya Pradesh (70 percent in three seats) and Punjab (66 per cent in two seats).
The counting of votes will be taken up on August 25.
Stakes are high for BJP in the bypolls as the party is in fray in most of the 18 seats and seeks to prove that its emphatic win in Lok Sabha elections was no flash in the pan and that Narendra Modi magic is not waning.
In Bihar, the exercise is as much a key trial of strength for BJP, which had won six out of the 10 seats in 2010 assembly election as for the "Mandal" politics of Lalu-Nitish combine seeking to stage a comeback in the state after their decimation in general elections.
The outcome in Bihar could also be a pointer to the mood of the people ahead of next year's assembly polls.
Karnataka saw a a close battle between BJP and the state's ruling Congress in the three assembly constituencies Chikkodi-Sadalga (81.30 per cent turnout), Bellary Rural (68.9) and Shikaripura (65) which have a total electorate of over 5.57 lakh.
For Chief Minister Siddaramaiah, a lot is at stake as he faced the first popularity test after Congress' not-so-happy show in Lok Sabha polls in which it managed to secure only nine of the 28 seats against a resurgent BJP's 17.
After its power-winning performance in 2013 assembly polls in Karnataka, Congress was hoping to replicate the success in Lok Sabha elections but was checkmated by BJP driven by Modi factor.
The by-polls are crucial for Siddaramaiah, looking to consolidate his position in the party amidst signs of discontent with the functioning of his government, and BJP Vice President B S Yeddyurappa whose son B Y Raghavendra has been fielded from Shikaripura.
Congress went all out not only to retain Chikkodi-Sadalga but also wrest from BJP Bellary Rural and Shikaripura.
In Punjab, an estimated 62 per cent polling was recorded in Patiala constituency, where former Union Minister Preneet Kaur (Congress), wife of former chief minister Amarinder Singh, is in fray, and 70 per cent in Talwandi Sabo.
Kaur, who had lost the Lok Sabha elections, is pitted against Bhagwan Das (SAD) and Harjeet Singh of Aam Aadmi Party (AAP).
More than 70 per cent of the electorate exercised their franchise in the three bypolls in Madhya Pradesh for Bahoriband, Vijayraghogarh and Agar assembly constituencies.