Objective To study the change characteristics of erythrocyte parameters in carriers of deletional alpha-thalassemia gene.Methods 389 patients with deletional alpha-thalassemia gene determined by the gap-PCR technique were classified into three groups based on different genotypes of alpha-thalassemia including silent thalassemia group,alpha-thalassemia trait group (265 ca-ses)and intermediate thalassemia group,and contemporaneous 188 healthy adults were randomly selected as the normal control-group(NC).The erythrocyte parameters including RBC,Hb,MCV,MCH,RDW were retrospectively analyzed and their differences were compared among aboved-mentioned groups by the analysis of variance and the multiple comparison.Results Alpha-thalasse-mia manifested by different degrees of microcyte hypochromia.There were statistically significant differences in the erythrocyte pa-rameters among various genotypes and phenotypes about erythrocyte indices(P <0.05).Moreover,the Hb,MCV and MCH values were lower than those in the control group,and had the decreasing tendency with the increase of deletedα-globin gene numbers;but the RDW value was higher than that in the control group,showing the increasing tendency,the differences had statistical siginifi-cance(P <0.05).Conclusion With the increase of deleted α-globin gene number,the characteristic of small-cell low-hemoglobin is more and more remarkable.RBC has a overall increase,while Hb,MCV and MCH have a decreasing tendency,and the heterogeneity of erythrocyte volume is increased.When MCV and MCH decreasing in high risk region,thalassemia should be highly suspected, but normal MCV and MCH can not exclude silent thalassemia and alpha-thalassemia trait.