It took place between 21 June and 14 July, with 22 stages covering a distance of 4,329 km (2,690 mi).

Anquetil then began helping Aimar win the Tour, to make sure and deny it to his then-enemy Raymond Poulidor.

[4] Shortly after this, a medical test showed Felice Gimondi, winner of the 1965 Tour de France, could not defend his title because he was physically not fit; his Salvarani team then decided not to start at all, so the number of teams was back to thirteen.

[5] The organisers then invited the Italian team Sanson (headed by Italo Zilioli and Franco Balmamion) to replace Salvarani,[6] but at the last moment they refused.

[9] The 1966 Tour de France started on 21 June, and had two rest days, in Luchon and Turin.

[10] The highest point of elevation in the race was 2,556 m (8,386 ft) at the summit tunnel of the Col du Galibier mountain pass on stage 16.

In the next stages, no big time differences were made, so Altig was able to defend his lead until the mountains.

A group including Lucien Aimar and Jan Janssen gained time on pre-race favourites Jacques Anquetil and Raymond Poulidor, and Tommaso de Pra won the race and became the new leader.

In the sixteenth stage, Julio Jiménez escaped in the Pyrenées, and he was followed by a group including Janssen, Anquetil and Poulidor, but without Kunde.

[17] In the eighteenth stage, Janssen wanted to attack, but Aimar and Anquetil stayed close to him.

Poulidor, sixth in the general classification, managed to escape, but Anquetil led the chase on him.

[17] Janssen became the first Dutch cyclist to reach the podium in the general classification in the Tour de France.

[19] The most important was the general classification, calculated by adding each cyclist's finishing times on each stage.

[27] In June 1965, the French government enacted a law that made doping in sports illegal.

This made knowingly taking doping explicitly not allowed in the Tour de France.

Judgement was made in 1969, and the appeal was successful: because it is almost impossible to prove that someone takes doping knowingly, the law was thereafter seldomly used.

[39] The organisation of the Tour de France was not happy with the riders' reactions on the doping controls.