More than 200 people in Ashbourne are having an extra-marital affair, a website states.
Illicit Encounters, a dating website specialising in extra-marital affairs, claims that 229 people in the town are cheating on their partner.
The data also says that 11, 446 in Derby, 707 people in Alfreton, 472 people in Belper and 304 people in Matlock are being unfaithful.
It is also claimed that in Ilkeston 434 people are cheating, with 204 in Ripley, 216 in Heanor and 88 in Bakewell.
The Berkshire town of Maidenhead was named the UK's Capital of Infidelity, where 1,316 people in the 63,580-person strong town are having an affair.
The site, which was created to let members meet others looking for an affair, while allowing them to stay with their long-term partner or spouse, compiled membership data of 140 UK towns and cities with a population above 50,000.
Mike Taylor, a spokesman for Illicit Encounters, said: "We have 850,000 registered users and when people do register they give their address and postcode which is how we can tell you how many people are having an affair in any given place.
"We are the most expensive dating site out there and charge men £139.99 a month for membership. Women can have a basic profile for no charge."
Mr Taylor said that of the 850,000 users, at any one time around 12 per cent were active members.
Top 10 UK towns for affairs
1 Maidenhead 1,316 affairs out of a population of 63,580 (2.07 per cent)
2 Livingston 1,080 affairs out of a population of 56,269 (1.92 per cent)
3 Farnborough 1,008 affairs out of a population of 65,034 (1.55 per cent)
4 Loughborough 877 affairs out of a population of 59,932 (1.48 per cent)
5 Bracknell 1,128 affairs out of a population of 77,256 (1.46 per cent)
6 Gravesend 784 affairs out of a population of 55,467 (1.41 per cent)
7 Beeston 702 affairs out of a population of 51,479 (1.36 per cent)
8 Aldershot 776 affairs out of a population of 57,211 (1.35 per cent)
9 Gosport 960 affairs out of a population of 71,529 (1.34 per cent)
10 Taunton 802 affairs out of a population of 60,479 (1.33 per cent).