Flow cytometric analysis of reticulocyte counts, using membrane-permeable fluorescent dye,thiazole orange, was evaluated as an alternative to the conventional new methylene blue method, and evaluated the referance values of mean channel fluorescence(MCF) in addition to routine reticulocyte count for normal adults. Eighty-eight clinical specimens from inpatients and outpatients in our hospital were analyzed reticulocyte counts by flow cytometer and simultaneously by conventional method. And 40 samples from healthy adults, 20 males and 20 females were analyzed reticulocyte counts and MCF by flow cytometer. We compared reticulocyte counts of new methylene blue method(X) and flow cytometry(Y), the correlation coefficient was 0.90(Y=0.81+0.77) in 88 patient samples(P>0.01). Reference values(mean 2SD) of reticulocyte count were 0.60-2.12 % in adult males(n=20), 0.60-2.23 % in adult females, values of females were slightly higher than those of males. And reference values of MCF were 44.4-66.0 in adult males, 41.3-72.1 in adult females. The flow cytometric fluorescence reticulocyte enumeration methods are efficient, rapid, and reliable for reticulocyte counting.