New methods for measuring body temperature are marketed regularly. In our department we used an electronic thermometer (Craftemp) which measured oral or axillary temperature. Since we doubted the accuracy of the measurements made with this device, we compared the values found using this thermometer with values from a conventional mercury thermometer, both in a thermostatic regulated water bath and when used clinically. There was good conformity between the results in the water bath. However, when the thermometer was used clinically, in half the patients there was a difference of 0.5 degrees C or more from the rectal temperature measured with a mercury thermometer. Most of the beds in our department are occupied by geriatric patients with age-related diseases. Many of them also have mental disturbances (e.g. dementia), which makes adequate cooperation during the measuring procedure uncertain. This study indicates that the electronic thermometer (Craftemp) is not suitable in a department like ours with many old disabled patients.