Swimming at the 1912 Summer Olympics – Men's 100 metre freestyle

The fastest two in each heat advanced. A tie for second in the seventh heat resulted in both swimmers advancing. In addition, the fastest third-place swimmer from across the heats also qualified for the quarterfinals.

Again, the top two in each heat advanced along with the fastest loser overall. Four of the qualified swimmers did not take part in their quarterfinal heats, and a fifth (Massa) did not appear due to a misunderstanding. Massa was later allowed to take part in the semifinals.

Further confusion struck the semifinals. Under the belief that the second round of the competition had been the semifinals, the American swimmers did not appear for the third round. This led to both semifinals being essentially walkovers, as the first had three swimmers and the second only one. Since the top two swimmers of each and the fastest third-place swimmer would advance, all four competitors had secured a place in the final before entering the water. Longworth swam in the first heat, despite suffering from what the official report referred to as "suppuration in the head".

The jury for the swimming events met and determined that a third heat should be held under special rules. If the winner of the extra heat were to beat the time set by the third-place swimmer of the first heat (1:06.2, a stiff pace but one which all three Americans had beat during the quarterfinals), he and the second-place finisher would advance. If the mark were not bettered, none of the swimmers from the third heat would advance. Massa, who had missed the quarterfinals due to a misunderstanding, was also allowed to start in the extra semifinal.

In the third heat, Kahanamoku not only beat Longworth's time, thus qualifying himself and Huszagh for the final, but bettered his own Olympic record which he had set in the first round. Huszagh out-touched McGillivray by a "hand's breadth" to take second place and the final qualification spot, though both finished well behind Kahanamoku and their own previous times. Massa did not finish the race.

Longworth was unable to continue competing due to illness and did not start in the final.

Kahanamoku was clearly in control by the halfway point, with a tight race between Huszagh, Ramme, and Bretting for the next three spots with Healy close behind them. It was Healy who took the silver medal, though, as he swam by the other three near the finish. Ramme fell back to fifth while Huszagh and Bretting finished separated by "[o]nly a decimetre".

Rank	Swimmer	Nation	Time	Notes
	Duke Kahanamoku	United States	1:03.4
	Cecil Healy	Australasia	1:04.6
	Ken Huszagh	United States	1:05.6
4	Kurt Bretting	Germany	1:05.8
5	Walter Ramme	Germany	1:06.4
6	William Longworth	Australasia	DNS