Thorium, uranium, and potassium contents of 10 bediasites, 12 philippinites, 8 australltes, and 5 indochinttes were determined using a non-destructive gamma-spectrometric technique. The average thorium, uranium, and potassium values of the 35 tektites counted were 11.8 ppm, 2.1 ppm, and 1.9% respectively. The bediasites show lower than average values (7.3 ppm Th, 1.8 ppm U, and 1. 8% K) while the philippinites are noticeably higher (14.6 ppm Th, 2.6 ppm U, and 2.0% K). The australites and indochinites show similar values (12.7 ppm Th, 2.1 ppm U, and 1.9% close to the total average. The bediasites seem to be definitely deficient in thorium content. An average Th/U ratio of 5. 4 was obtained. Although valid regional differences could not be determined, a definite hierarchy of decreasing thorium and uranium values from australttes and indochinites, to bedtasttes was clearly established and confirmed by total alpha-counting methods. Both the individual Th/U ratios and the total alpha-determinations indicate a single related occurrence for the Pacific Ocean or Far Eastern tektites consisting of the australites, indochinites, javanites, and philippinites. The microsites of the alpha-emitters were investigated by autoradiography and it was determined that the radioactivity in tektites is homogeneously distributed and of a low flux.