A procedure is proposed to normalize enzymatic reaction velocities measured in separate experiments. After calculation of the Km and maximum velocity in each individual set of data, the velocities measured in each experiment are reanalyzed by regression analysis with the constraint that they yield a Km identical to the geometric mean of the individual Km's calculated originally. The V derived from this second analysis can be taken, in each experiment, as the reference value relative to which all reaction velocities are normalized. All normalized velocities are eventually pooled together to establish the final regression line. This relatively simple and reliable procedure overcomes several difficulties otherwise encountered when the kinetics of an enzymatic reaction are judged from data collected in separate experiments.