Wearable thermometers are popular devices for measuring body temperature during fever, as well as for monitoring basal temperature in women. They are easy to handle, inexpensive, accurate and provide continuous recordings. Most wearable thermometers are connected to a smart phone or tablet to display data. Many types of wearable thermometer are available, such as touch, patch and invisible (radiometric) types. In this review, we describe and discuss currently available wearable thermometers.