Reference 3940 was launched in 1985 and discontinued in 2007. It has always been regarded as rather a special watch to collectors and certainly a significant reference in the modern history of Patek Philippe. The 3940’s reputation is further enhanced by the knowledge that the then head of the company, Philippe Stern, chose to wear the model as his everyday watch.

In the 1980s, few complicated wristwatches were generally available, so that the launch of the reference 3940 (at the same time as the perpetual calendar chronograph reference 3970) was a revelation. Its caliber 240-Q movement with micro-rotor enabled the watch to be not only complicated but slimmer at only 9 mm thick. The rotor is made of 22K gold to ensure that the small rotor provides enough weight to power the watch. The model was available in yellow, pink and white gold and platinum.

The design of the dials, in common with many Patek Philippe references, naturally evolved in over twenty years of production resulting in three clearly defined series and some rare variations.

- the 1st Series produced from 1985 to 1988
- the 2nd Series produced from 1988 to 1998
- the 3rd Series produced from 1998 to 2007

Examples of reference 3940 are illustrated and described in: Patek Philippe Museum - Patek Philippe Watches - Volume II, p. 300, and in: Patek Philippe Wristwatches by Martin Huber & Alan Banbery, second edition, pp. 292-294.