The elections - regarded as a test of popularity of the respective state governments as also of the Bharatiya Janata Party which held many of these seats - were generally peaceful.
However, one person died of a heart attack following a clash in Uttar Pradesh while a few other political workers sustained injuries in violence elsewhere.
The elections to the three Lok Sabha constituencies became necessary after three political stalwarts - Prime Minister Narendra Modi, Samajwadi Party chief Mulayam Singh Yadav and Telangana Chief Minister K. Chandrasekhar Rao - resigned from Vadodara (Gujarat), Mainpuri (Uttar Pradesh) and Medak (Telangana) respectively.
Simultaneous by-polls were held to three assembly seats in Assam, nine in Gujarat, four in Rajasthan, 11 in Uttar Pradesh, two in West Bengal and one each in Andhra Pradesh, Chhattisgarh, Sikkim and Tripura.
The biggest turnout - 88 percent - was recorded in the tiny northeastern state of Tripura where a by-election was held for the Manu assembly seat.
In the western state of Gujarat, voting was slow.
Modi vacated Vadodara after he was elected to the Lok Sabha from two places, including Varanasi in Uttar Pradesh.
Residents of several colonies in Vadodara city, where flood waters created havoc three days ago, boycotted the voting as their demand of constructing roads was not met.
Over 53 percent voters cast their ballot in by-polls to one Lok Sabha and 11 assembly constituencies in Uttar Pradesh.
At a polling booth in Saharanpur, supporters of the BJP and the Congress clashed during which a person suffered a heart attack and died.
Officials rushed to the spot, pacified the people and took the body for a post-mortem examination.
In another incident, BJP's ally Apna Dal MP Anupriya Patel and Samajwadi Party supporters were engaged in a verbal spat at a polling booth in Rohania.
Samajwadi Party chief Mulayam Singh Saturday said his party will sweep the polls and will win the Mainpuri Lok Sabha and all the 11 assembly seats.
Mainpuri with 1,647,176 voters is crucial for the Samajwadi Party as the seat has been held by the party for over two decades.
In Rajasthan, by-polls to four assembly seats saw 65 percent of the voters take part.
"Polling was peaceful and as per tentative information, 65.87 percent of the electors cast their votes till 7.15 p.m.," an election department official told IANS.
Over 60 percent of the electors exercised their choice in Medak Lok Sabha constituency and Andhra Pradesh's Nandigama assembly seat.
Workers of the ruling Telangana Rashtra Samithi (TRS) and the opposition Congress clashed at Kothapet in Medak constituency. Police used force to disperse the clashing groups.
Villagers in Peddapur boycotted the polling to protest lack of proper roads and other development work.
In Gangapur village, people did not participate in the voting because election officials did not set up a polling centre near their village.
Telangana Chief Minister K. Chandrasekhar Rao, whose resignation caused the vacancy in the Medak parliamentary seat, and his wife cast their votes in their native Chintamadaka village in Siddipet mandal.
Amid allegations and counter-allegations between political rivals in West Bengal, the by-elections went off peacefully.
"Basirhat South recorded 79.59 percent, while in Chowringhee only 47.13 percent polling was recorded," Chief Electoral Officer Sunil Gupta said.
Gupta said the polling was "free, fair and peaceful" with only one incident of a scuffle between BJP and Trinamool activists in which three people were injured. Women CPI(M) supporters were also allegedly attacked by Trinamool supporters in Kolkata although the latter rubbished the charges.
The three assembly constituencies in Assam saw an average of 66 percent polling till 5 p.m. even as balloting continued in some booths.
Polling was peaceful across the three constituencies of Silchar, Lakhipur and Jamunamukh.
In Chhattisgarh, polling in the Antagarh assembly ended with 40-45 percent voters casting their ballot.
Amid great enthusiasm, over 79 percent of the electorate gathered at the polling booth for the Rangang-Yangang assembly constituency by-poll in the landlocked Himalayan state of Sikkim.
There were lengthy queues in front of the 14 polling stations as men and women in colourful clothes stood patiently to exercise their democratic right.
The by-poll was necessitated after Chief Minister Pawan Chamling resigned from the seat and retained Namchi-Singhithang after the April assembly polls.