A carborne gamma-ray spectrometric survey normally provides preliminary reconnaissance coverage of the radioelements in the topmost part of the earth's crust. However, a radiometric survey under certain conditions can be used for geologic mapping. In the present paper this approach was used to differentiate various lithological units within the Neogene formations east of Homs. The total radioactivity and the ground concentrations of potassium, uranium, and thorium were obtained over an area of 294 km 2 . Despite, generally, the small variations in the contents of these variables, it was possible to categorize some rock units in the study area based on their radiometric response.