Mennea, who was born in Barletta, in the Italian region of Puglia, started his long international athletic career in 1968 when he took part in a junior race in Termoli and he was registered in AVIS Barletta club;[2] in 1971, he won the first of his 14 Italian outdoor titles in the 100 and 200 m. He went on to win two indoor titles in 60 m and 400 m, along with five Mediterranean Games gold medals in 100 m and 200 m. He competed at the European Championships with a third place in the 4 × 100 m relay.

[citation needed] In 1979, Mennea placed first in the 100 metres and second in the 200 m behind Allan Wells of Great Britain in the European Cup.

However, in the straight Mennea gained ground and passed Quarrie and Leonard and at the very end of the race, just beating Wells, winning the gold by a mere 0.02 seconds.

[3][5] In 1983, in Cassino, he clocked a manual 14.8 seconds in 150 metres, a world best time that he held until it was bettered by Usain Bolt in Manchester in 2009.

Mennea, known in Italy as the la Freccia del Sud ("the Arrow of the South"), then announced his retirement, allowing himself more time for his studies.

Again, Mennea made a comeback, and competed in his fifth Olympics in Seoul, where he was the flag bearer: he qualified for the quarterfinals of the 200 m, but he decided to withdraw from the competition and did not take part into the next round.

In an interview to an Italian newspaper in 1987 he told that in 1984, during the Summer Olympics in Los Angeles, an American physiotherapist proposed a doping treatment to him.

Back in Italy he tried two injections of human growth hormone but the crisis of conscience he got was so important that it induced him to retire from activity: "I realized that in my life I was looking for everything, except for that.

[4] On the day of his death, the Italian Railways announced that the new superfast train Frecciarossa ETR 1000, entering service in 2014, would carry his name.