Airborne radioactivity surveys in the Mojave Desert region Kern, Riverside, and Bernardino counties were made in five areas recommended as favorable for the occurrence of radioactive raw materials: (1) Rock Corral area, San Bernardino County. (2) Searles Station area, Kern county. (3) Soledad area, Kern County. (4) White Tank area, Riverside and San Bernardino counties. (5) Harvard Hills area, San Bernardino County. Anomalous radiation was detected in all but the Harvard Hills area. The radioactivity anomalies detected in the Rock Corral area are of the greatest amplitude yet recorded by the airborne equipment over natural sources. The activity is apparently attributable to the thorium-beating mineral associated with roof pendants of crystalline metamorphic rocks in a granitic intrusive. In the Searles Station, Soledad, and White Tank area, several radioactivity anomalies of medium amplitude were recorded, suggesting possible local concentrations of radioactive minerals.