Although there is a large body of research addressing infidelity, no study, to our knowledge, has specifically addressed infidelity in doctors and nurses and the correlation with work hours, schedule and other variables. This research aimed to know the incidence of and factors related to infidelity among doctors and nurses. A descriptive study was carried out, studying the association of certain variables. In total, 367 volunteer participants completed an online survey. Of them, 21% either have or have had an unfaithful relationship. The majority (81.7%) were doctors. Men were 4.3 times more unfaithful than women, with these differences being statistically significant (OR = 4.37, p < 0.001). Of the participants involved in an unfaithful relationship within the work area, the majority were men. Likewise, those who reported having had sex in the doctor’s room on duty were also men, with these differences being statistically significant (OR = 12.81, p < 0.01). The night emergency schedule was 60% more frequent in unfaithful people, and these differences were statistically significant (OR = 12.43, p < 0.01). There is a significant rate of infidelity in doctors and nurses. Men are more likely to be unfaithful than women are, and people who work nighttime emergencies are more likely to be unfaithful.