~3H-TdR-autoradiography and Feulgen reaction were carried outsuccessively on smear preparations of single cells.The proportion ofproliferating cells(S,G2)labeled by silver grains was counted,thenFeulgen-density of unlabeled cells(G1)in the same slide wasdetermined cytophotometrically.Although the labeling index of theactive lymphocytes induced by PHA in vitro reaches 30.17%,isotope seems unable to be incorporated into the cells of juvenilepolyps.Only a small number of cells in the various types ofadenomatous polyps and adenomas were labeled by silver grains.The DNA content(24.06)of the lymphocytes in prometaphase(4C)is used as a reference standard,DNA index(DI)was calculated fromthe ratio of DNA content in the analyzed cells to normal diploidvalue(12.03).The cellular DNA content in 5 cases of juvenile polypsis mainly within normal diploid range(mean 12.06,DI=1.00),however,hyperdiploid abnormality prevails in 5 cases of adenoma-tous polyps and adenomas(mean 14.36,DI=1.19).The difference ofDNA value between the two groups of polyps is statistically signifi-cant.Because the former group has no apparent relation to adenocar-cinoma,while the latter group frequently tends to undergo malignantchange,these data would lead us to speculate that abnormal DNAcontent or aneuploidy may be considered as a probable sign ofmalignancy. ~ 3H-TdR-autoradiography and Feulgen reaction were carried outsuccessively on smear preparations of single cells. The proportion ofproliferating cells (S, G2) labeled by silver grains was counted, thenFeulgen-density of unlabeled cells (G1) in the same slide wasdetermined cytophotometrically .Although the labeling index of the active lymphocytes induced by PHA in vitro reaches 30.17%, isotopes unable to be incorporated into the cells of juvenile proteins. Only a small number of cells in the various types of adenomatous polyps and adenomas were labeled by silver grains. DNA content (24.06) of the lymphocytes in prometaphase (4C) is used as a reference standard, DNA index (DI) was calculated from the ratio of DNA content in the analyzed cells to normal diploid value (12.03). The cellular DNA content in 5 cases of juvenile polypsis mainly within normal diploid range (mean 12.06, DI = 1.00), however, hyperdiploid abnormality prevails in 5 cases of adenoma-tous polyps and adenomas (mean 14.36, DI = 1.19) of DNA value between the two groups of polyps is statistically signifi-cant.Because the former group has no apparent relation to adenocar-cinoma, while the latter often frequently to undergo malignantchange, these data would lead us to speculate that abnormal DNAcontent or aneuploidy may be considered as a probable sign of malignancy.