The age specific incidence of the palmomental reflex (PMR) has been investigated in persons without any former or present evidence of a neurological or mental involvement. Also excluded were persons with hypertension, diabetes mellitus, thyroid dysfunction, alcohol abuse and other diseases as these could effect the central or peripheral nervous system. From the newborn period up to the age of 20 years the incidence of the PMR was between 3,3% and 20%, the differences being statistically insignificant. After the age of 20 years the incidence of the PMR rises with increasing age, the rise being approximately 10% per decade. There was no asymmetry of the PMR in persons without affection of the nervous system and who met the above mentioned criteria. Since a symmetrical PMR can be found in a considerable percentage of persons with no indication of a neurological or mental involvement, it should not be considered as a pathological sign. An asymmetrical PMR was found in 20 persons who did not meet the above mentioned criteria. In 5 out of these 20 persons additional neurological signs could be detected. 9 patients had histories of brain trauma, meningitis, cerebrovascular disease and polyneuropathy. 9 others were suffering from severe cardiovascular disease, carcinoma and alcohol abuse. In only one patient, although presenting with some neurological signs, no relevant history could be detected. An asymmetrical PMR, therefore, must be considered as a discrete indication of an involvement, either of the central or the peripheral nervous system. The PMR has no certain localizing significance.