More than 500 people in Eastbourne are having an affair, according to the official 2015 infidelity index.
The index, released today by married dating site IllicitEncounters.com, shows the number of people having affairs in every area of the UK.
According to the website, 518 married people in Eastbourne are having an affair, compared to 515 the previous year.
Hailsham has also seen an increase in the number of people cheating on their partners, with 343 people signing up to the Illicit Encounters website this year compared to 317 in 2014.
Seaford bucks the local trend and has seen a rise in the number of people staying faithful to their other halves, with 254 people having an affair this year compared to 301 last year.
The index has revealed Beeston as the most unfaithful town in the UK and Craigavon in Northern Ireland as the most faithful.
To see the 2015 rankings, visit www.infidelityindex.co.uk.