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Human data are used to obtain (MPC)wvalues for continuous occupational exposure to Sr90, Sr89and Sr85. A three-exponential model is found to give an empirically adequate representation of the data on retention and excretion of strontium by grossly normal adults for a period of 200 days following intake. The third exponential is selected to be roughly consistent with the data on stable strontium in diet and in bone of adults, as well as in fair agreement with the estimates of bone turnover rates by ROWLAND. The use of a power function to describe retention is summarized. Also, MPC values are estimated for Sr90by the use of the observed ratio, O.R., and from the diet-bone data on stable strontium. These various models are discussed briefly as to their adequacy for applied health physics. It is found that all these models indicate an (MPC)wfor Sr90which is higher by a factor of 4 or more than that recommended currently by ICRP and NCRP.