Recording an accurate body temperature is important to assess an animal's health status. We compared temperature data from sedated cynomolgus macaques (Macaca fascicularis) to evaluate differences between rectal, infrared (inguinal and chest), and implanted telemetry techniques with the objective of demonstrating the diagnostic equivalence of the infrared device with other approaches. Infrared thermometer readings are instantaneous and require no contact with the animal. Body temperature data were obtained from 205 (137 male, 68 female) cynomolgus macaques under ketamine (10 mg/kg IM) sedation over a 3-mo period during scheduled physical examinations. Infrared measurements were taken 5 cm from the chest and inguinal areas. We evaluated 10 (9 functional devices) sedated cynomolgus macaques (5 male, 5 female) implanted with telemetry units in a muscular pouch between the internal and external abdominal oblique muscles. We determined that the mean body temperature acquired by using telemetry did not differ from either the mean of inguinal and chest infrared measurements but did differ from the mean of temperature obtained rectally. In addition, the mean rectal temperature differed from the mean of the inguinal reading but not the mean of the chest temperature. The results confirm our hypothesis that the infrared thermometer can be used to replace standard rectal thermometry.