A linear algorithm for the rapid calculation of local rate constants is proposed. The method is applicable to the three-compartment models currently used in the analysis of positron camera measurements with [11C]methionine, [11C]deoxyglucose, and [11C]glucose. The same technique can also be used for the regional measurement of local blood flow with the aid of a freely diffusible tracer. The algorithm was applied to measurements on humans with [11C]glucose. As a comparison, the same data were also analyzed with a standard nonlinear technique. Good agreement between the two methods was obtained.