According to the research, three fifths of affairs start in the office, with most trysts taking place between 2pm and 3pm as people sneak off during their lunch breaks, reports the Telegraph.
In around half of cases, cheating partners are found out through indiscreet mobile phone text messages, emails betray one in five and a further one in 10 are given away by anonymous letters, according to the survey by the Italian Association for Family Lawyers.
Seven in 10 affairs are one-off flings, with the rest more long-term relationships.
Gleeden.com, which describes itself as "the premier international dating website for married people," has 90,000 Italians signed up to it.
Infidelity is most prevalent in Milan, with Rome a close second.
Until 1981, Italian law recognised the principle of honour killings, with courts entitled to hand out more lenient sentences to men convicted of murdering their cheating wives.
Nowadays, around half of cases of infidelity are tolerated by long-suffering partners, the survey found.