The Two Thousand Guineas Stakes is a Group 1 flat horse race for three-year-old thoroughbreds (excluding geldings). It is run over a distance of 1 mile (1,609 metres) on the Rowley Mile course at Newmarket Racecourse, Newmarket, Suffolk, England in late April or early May. It is one of five British Classic Races.

It was first run on April 18, 1809 and takes its name from the original guaranteed prize fund of 2,000 guineas (worth approx. £110,000 today — 1 guinea = £1 1s, or £1.05).

The race takes place early in the season and there may be little previous form for that year - last season's two-year-old form is usually taken as the most reliable guide to predicting the outcome. Although eligible, fillies rarely take part in the race any longer.