[en] Estimates, based on an empirical model and computer program (Ellis, Healy, Shleien and Tucker, HEW publication (FDA)76-8015), have been calculated and are presented on the mean active bone marrow dose to adults from diagnostic radiography, fluoroscopy, and dental radiography as practiced in the United States in 1970. The annual per capita mean active bone marrow dose in 1970 to adults from the above practices is estimated to have been 103 mrad; 77 percent, 20 percent, and 3 percent from radiographic, fluoroscopic and dental examinations, respectively. Examinations of the upper and lower abdomen contribute approximately 39 percent each to the total mean active bone marrow dose for adults; those of the pelvis, 4 percent; the thorax, 12 percent; and head and neck examinations (including dental) contribute about 6 percent. The per capita mean active bone marrow dose for various age groups is discussed. Contributions to the dose within a given age group from different examinations indicate that in the 15 to 34 year age group lumbar and lumbosacral spine examinations contribute most to the mean active bone marrow dose. Thereafter upper Gi series and barium enemas are the highest contributors. Mean active bone marrow doses for children are not estimated in this presentation due to insufficient data. However, the lower rate of use of diagnostic x rays (except dental) in children would reduce the annual per capita mean active bone marrow dose for the entire population to approximately a maximum of 77 mrads. The results may be viewed relative to several surveys of radiation doses from diagnostic radiology performed in other countries which reported annual per capita mean active bone marrow doses varying from 30 to 189 mrads for their entire populations, and with natural background for which the annual per capita whole body and bone marrow dose in the United States is approximately 130 and 86 mrads, respectively