Human data on plutonium deposition, internal distribution, and excretion have been obtained by observations after accidental occupational exposures, long- term follow-up studies on plutonium workers, and autopsy tissue analyses. No significant harmful effects have been noted in humans, although a small foreign- body type nodule around dermal implantations of plutonium has been described in eight persons. Methods used to estimate body burdens by urinary excretion values appear to be conservative generally compared to autopsy tissue burdens. Variations in autopsy tissue distribution appear to be related to the conditions of the plutonium exposure including mode of exposure, particle size, chemical composition, solubility in serum or tissue fluids, and time after exposure for internal redistribution. An important conclusion of this human data survey is the recognition of the inestimable value to be gained by continued careful studies on the life history of workers with higher plutonium exposures. (auth)