Reconstruction of the primary indicator-dilution curve is accomplished by exponential curve-fit from a set of points obtained on the downslope of the curve. Curve-fit is simplified by requiring entry of indicator concentrations (Yi) only, where time increments (Xi) are made self-generating in the program. Similarly, calculation of mean transit time requires only the entries of Yi. Stored values supply the needed quantities for calculations of cardiac output and the central blood volume as defined by the injection and the sampling sites. The Texas Instrument TR 52 model hand-held programmable calculator is utilized in this program but it should be adaptable to other programmable calculators. The present program provides a procedure for rapid reconstruction of the primary indicator-dilution curve, and hence calculations of cardiac output, mean transit time and central blood volume.