The present study performed an experiment to validate the histogram summation technique developed for measurement error minimization of respiratory air flow rate2). Five sets of manual stroke operation data(MSO#1 5) of 1 [LI each were acquired at varying speeds. Selected sets of these data were used to estimate the conductance correction factors reflecting the resistance-flow character -istics. Then the correction factors were applied to different sets of the data to evaluate mean SD of the volume measurement error. When the resistance was linearly compensated without conductance correction, the relative error was 2.3% marginally within the ATS standard limit of 3%. With the histogram summation techinque applied, it has dramatically decreased down to within 1%. For a newly input flow data, the error was maintained within 1.5%. Therefore, the histogram summation techinque minimized the measurement error consistently and reproducibly. With increased number of strokes included in the correction factor estimation process, the error decreased at a rate of 0.5 [mL!S0strokesj. However, no more than 50 stroke data were necessary to keep the measurement error within 1.5%. This corresponded to only 25 MSO, thus the histogram summation technique has been demonstrated to be consistent, reproducible, and practical technique for measurement error minimization of respiratory air flow rate.