A comparison between 70-blood-donor and 70-health-control blood lipoids,blood composition,and hemorrheological indexes by paired analysis method basedon occupation,sex and age was made.Paired T-test showed that though severalindexes of the blood donors reduced remarkably,they were still within the normalphysiological limits,There were no abnormal findings through physical examinationand ECG,indication that according to the general physique and present diet condi-tions of Chinese population.It is safe to donate 300ml blood once at intervals of three months.