A model elucidating the relationships between blood radioactivity, the renogram curve, and urine radioactivity, as a function of time, is derived. Estimation procedures have been devised which use the data from three curves at once to estimate parameters common to the three curves, and which also estimate parameters unique to the individual curves. A program has been written for the RPC 4000 computer to perform the estimation. It was found that some model in which six different exponential parameters could be justified instead of the two proposed by the model could provide a significantly better fit of the data (P \u3c .001), but that the fit under the hypothesis was still quite good
