2018 IAAF World U20 Championships – Men's 800 metres

The men's 800 metres at the 2018 IAAF World U20 Championships was held at Ratina Stadium on 13, 14 and 15 July.

Heats
Qualification: First 3 of each heat (Q) and the 4 fastest times (q) qualified for the semifinals.

Semifinals
Qualification: First 3 of each heat (Q) and the 2 fastest times (q) qualified for the final.