BackgroundTo examine the accuracy of noncontact tympanic (NCT) temperatures in outpatients, we conducted a prospective study comparing NCT temperature with temperatures obtained by oral mercury thermometers.Methods:\MThe study included 410 patients in whom oral and NCT temperatures were obtained.Results:—Mean oral temperature was 36.47 ± 0.44°C and mean NCT temperature was 36.36 ± 0.49°C. On paired-sample, two-sided t-testing, oral temperature differed significantly from NCT temperature, with aP-value < 0.0001. The difference between simultaneous oral and NCT temperatures was ≥ 1°F; in 63 cases, oral temperature was higher than NCT temperature.ConclusionWe conclude that NCT temperature measurement is not reliable in an internal medicine outpatient clinic setting.