Liam Fox is out, Theresa May takes the lead
Fox was the poorest performing candidate out of five – the others are May, Michael Gove, Stephen Crabb and Andrea Leadsom.
Fox got 16 votes, Crabb received 34, Gove had 48, Leadsom 66 and May got 165.
Mrs May's tally amounted to exactly half of the 330 Conservative MPs, but was a majority of the 329 voting.
That guarantees her a place in the final run-off ballot of Conservative members unless she loses supporters to one of her rivals over the next few days.
Commenting on this evenings result, Mrs May said: "I am pleased with this result, and very grateful to my colleagues for their support today. There is a big job before us: to unite our party and the country, to negotiate the best possible deal as we leave the EU, and to make Britain work for everyone. I am the only candidate capable of delivering these three things as Prime Minister, and tonight it is clear that I am also the only one capable of drawing support from the whole of the Conservative party. I look forward to continuing the debate about Britain's future - in Parliament and across the country."
The ballot took place at the Parliament's Committee Corridor, with MP Charles Walker overseeing the vote.
Further rounds of voting will take place this Thursday and the following Tuesday until two candidates remain.
The two candidates who top the final round of MPs' votes will go forward to a postal ballot of party members.
The winner is due to be named on the 9th of September.